June 15, 2016

Bug Fixes

June 9, 2016

Bug Fixes

Oneline Diagrams: When reading a KML diagram from ERCOT if a transmission line was encountered which did not exist in the power system case, an access violation occurred. This has been fixed so that instead the unlinked transmission line is created without an access violation occurring.

Oneline Diagrams: Fixed a problem reading a KML diagram from ERCOT. It was initially linking the power flow case transmission line to the display object, but when opening the dialog to show unlinked objects the lines would become unlinked.

June 2, 2016

Bug Fixes

Transient Stability: Modified the svsmo1, svsmo2, and svsmo3 models so that if the slow B control is not active in the power flow input data, then we ignore the Vrefmax and Vrefmin values in the stability model. Vrefmax and Vrefmin are really part of the slow B control in the power flow, so if they're not active in the power flow model, it makes sense that they also not be active in the stability model.

Transient Stability: Simulator had previously been treating the input to PSS2B when code 3 used as as Pelec - PelecInitial. We have found that it is intended to be Pelec directly instead. This had never mattered previously because the first block on PSS2B was a washout block and thus any constant input offset was completely removed anyway. However, PSS2B has input limits Vs2max and Vs2min so this distinction would matter if these limits were specified. PowerWorld had never seen a model with input limits that would be active however, so this had never been noticed. This has now been fixed.

May 19, 2016

Bug Fixes

May 11, 2016

Bug Fixes

Fault Analysis: Fixed a bug when building the positive and negative sequence admittance matrices. If there were 2 or more parallel transformers in the model, the off-diagonal elements in the admittance matrices were not correctly combining all of the transformer admittances, but rather was only putting one of the transformer admittances in the off-diagonal and was ignoring the rest of the parallel transformers.

Transient Stability: When a negative ThetaMin value is specified for wind pitch controller WT3P, WT3P1, or WTGPT_A model, this can be used by the WT3T/WT3T1/WTGT_A model to determine it's Theta0 value. In this situation however, the initial output of the WT3P/WT3P1/WTGPT_A model could be either ThetaMin or 0.0 (zero). Both will result in the appropriate initial output from the Aerodynamic model. Previously Simulator was initializing this value to ThetaMin which appeared OK, but this equilibrium point is an unstable equalibrium. Simulator has been changed so that when ThetaMin is negative, the initialized output of the pitch controller is set to 0.0 (zero).

April 28, 2016

Bug Fixes

Fault Analysis: Fixed bug in the table listing multiple steady state faults which prevented the user from editing the fault impedance of the fault in that table.

Power Flow Solution: Fixed a very obscure bug that would only occur when two Continuous SwitchedShunt objects had different regulated buses AND those regulated buses were connected by very low impedance branches. In this situation the switched shunt control might result in one shunt moving slow upward and the other moving slowing downward until either the solution ran out of Voltage Control Loop iterations or one of the shunts hit a maximum or minimum Mvar limit. Simulator has been modified so that in situations like this the the switched shunts' control algorithms do not fight against one another. This was first seen in a WECC case (26HW1ae.epc) with switched shunts at bus number 56485 and 54159.

March 4, 2016

Bug Fixes

Integrated Topology Processing (ITP): Fixing bug with shunt consolidation when saving a full topology case to a consolidated case. The voltage was not being set when closing a breaker (as part of closing a breaker and switching a shunt's status) so that it is detected by the consolidate shunt to blocks code. Now the voltage is set when the breaker is closed.

Integrated Topology Processing (ITP): Mvar output of shunts connected to open breakers was not set correctly after the consolidated case had been saved. This has been fixed.

February 18, 2016

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): When reading an AUX file that had a CoreType, IsAuto, GICModelTypem, or GICManualCoirR value for a transformer which was blank, an error would occur. This has been fixed.

Optimal Power Flow (OPF): Fixed an access violation that could occur when running OPF.

Power Flow Solution: Fixed bug that could cause SVSMO1 and SVSMO2 switched shunts to move when they should not.

Transient Stability: When in the middle of editing a float or integer value on the plot designer AND then switching to a different part of the plot it was possible for the value you had been editing (for example the vertical axis maximum) to then propagate to the new part of the plot you were navigating too. This has been fixed.

February 8, 2016

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Added field with Sim_Solution_Options to enable/disable DFACTs control globally.

Contingency Analysis: Access violations could occur if deleting three-winding transformers that are part of a contingency element. This has been fixed.

File Formats: The option to disable SVC control globally was not being saved to PWB files. This has been fixed.

File Formats: The option to disable DFACTs control globally was not being save to PWB files. This has been fixed.

File Formats: Fixed error setting generator statuses on buses that are categorized as load buses in the Bus section of the RAW file. Previously only the first generator at the bus was being properly identified at a load bus and set offline. But any other bus read at the same terminal bus would be treated as if it was being connected to a generator bus, regardless of the bus category in the RAW file, because after the first bus was connected there (even out of service) Simulator was treating the bus as a generator bus from that point forward. Now all generators inserted at a bus categorized as a Load bus will be inserted out of service.

Integrated Topology Processing (ITP): When saving a full topology model to a consolidated case, shunts that are connected to the same superbus by open breakers will be merged into a single shunt with blocks.

February 2, 2016

Bug Fixes

Case Information Displays: Model Expressions that link to many other model expressions can cause the display of case information displays for objects that use model expressions to be very slow. This includes Model Conditions, Model Filters, and Remedial Actions. This problem has been fixed.

January 20, 2016

Bug Fixes

Contingency Analysis: If a contingency that implements no actions follows a contingency that hit reserve limits, the contingency that implements no actions will have reserve limits reported with it as well because this flag was not getting reset. This has been fixed.

Fault Analysis: Fixed application of the correct units (pu or amps) on fields displaying fault currents on the oneline.

File Formats: When writing to EPC and RAW files and there are more than 11 points in an impedance correction table, the points need to be reduced so that there are only 11. This had been permanently changing the impedance correction tables instead of just temporarily during the file save process. This has been fixed.

File Formats: Made some modifications to reading RAW file that supports ERCOT MOD generated file that is being appended to another case. The file contained another comment symbol (@!) at the end of several lines. The first line (title) also was read entirely as a comment since it started with a /, which caused the case ID section to be read incorrectly, and the first bus in the bus list was lost. I changed it so that now the first three lines have to be the case ID section, with no comments at the beginning of the RAW file.

General: Fixed including area transactions as part of difference flows. You wouldn't get a difference if you set the difference flows base case and then opened a different case.

General: Removed some confusing messages in the log about switched shunts at the same bus having conflicting regulated buses. These messages could occur when one of the shunts was actually off control due to the area setting for switched shunt control. The problem was only with messages. The actual control of these devices was correct.

Power Flow Solution: Fixed a bug with not using the correct minimum limit for SVC type SVSMO3. This bug was introduced in the Dec. 18, 2016 patch.

Power Flow Solution: When using the Fast Decoupled Power Flow, solution problems could exist or access violations could result due to generators switching between being on AVR control and not on AVR control. This has been fixed.

Power Flow Solution: Generators that are on line drop compensation control that are no longer able to maintain this control will switch to PQ buses. This could cause power flow solution problems if the mismatch calculations are not updated for the change from PV to PQ bus. This has been fixed.

January 13, 2016

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed an access violation that could occur when using the STAR option to automatically determine the star bus number of a three-winding transformer when loading an auxiliary file.

January 6, 2016

Bug Fixes

File Formats: Fixed bug in writing out the Qtable section to a Version 19 EPC file if a generator had exactly 10, 20, etc. (multiple of 10) points on the qtable. In this situation we would write out a slash (/) character at the end of the record inappropriately.

Integrated Topology Processing (ITP): Bus shunts were not being restored correctly from a system state stored while the case was consolidated to a system that is not consolidated. There would probably have also been problems with a state stored not consolidated and restored consolidated. Restoring the bus shunts has been fixed no matter what consolidation status you are in while storing or restoring.

Sensitivity Calculations: In the general LCDF calculation, the result will be returned as 0 if an open line is between two islands.

Transient Stability: Modified some strange blinking behavior that could occur when configuring transient stability dialog to update frequently during the simulation run.

December 22, 2015

Bug Fixes

December 18, 2015

Features and Improvements

Contingency Analysis Tool: When displaying LODF/LCDF calculations as part of the Contingency Sensitivities tool, if a branch causes the island topology to change, 'Island Change' will be reported instead of the LODF/LCDF and all other values will be blank. The Contingency Sensitivities Tool is available under the right-click menu of a particular contingency violation.

Simulator Automation Server (SimAuto): Modified so that when running a SimAuto instance we never write the list of Recently opened files to the registry. This should only be modified when opening files in the user interface

Bug Fixes

Distributed Computation: When running distributed computing tools it is possible for multiple instances of Simulator to close simultaneously and then try to write to the windows registry all at the same time. This was causing a conflict resulting in dialogs appearing indicating you can't write to the registry. This has been fixed by not writing to the windows registry from a SimAuto instance that was launched by PowerWorld's distributed computing tools.

Distributed Computation: When running distributed Transient Stability, Simulator was going through and validating the transient stability models for every contingency. This is unnecessary, and it is only necessary to validate against the largest time step, so now validation is only done once on the largest time step.

Distributed Computation: When running distributed Transient Stability, Simulator was continuing to write TSR files even when the user had chosen not to store to hard drive or to RAM (you might do this if you were only looking at the transient limit monitors.) This has been modified for now so that a TSR file is still written but it is configured so it doesn't store anything (it will be about 4 KB). We will likely remove this shortly as well.

Power Flow Solution: Fixed an issue with min and max of svcs that provide continuous Mvar control. In some situation they would become stuck at their min or max limit and not back off the limit when appropriate.

Simulator Automation Server (SimAuto): Added additionally checking to ensure that only one instance of SimAuto can write to the registry at a time.

Transient Stability: When writing an AUX file containing the Min/Max results for generators, some switched shunts that model SVCs were being included in this AUX file. These have been removed.

Transient Stability: A bug from the December 7 patch was introduced when storing results in transient stability for the rotor angle. This value was always being stored as 0.0, even for synchronous machines. This has been fixed to properly return the rotor angle. (Note: this was only a bug in Version 18 patch. Version 19 was correct).

December 15, 2015

Bug Fixes

Contingency Analysis: When choosing to show contingency element definitions in the user interface "by label", Simulator was still showing the definitions by number. This has been fixed so that the GUI shows them by label when chosen.

Transient Stability: fixed error with the Distribution Equivalent. In Nov 25 patch we added support for transformer switching in the distribution equivalent load model. In this addition however we were not obeying the LTC flag of zero which indicated that tap switching was not available for the transformer and were instead switching all transformers. This has been fixed to switch those transformers for which this control is enabled.

Transient Stability: do not include initialization limit checking for LD1PAC stall voltage when the bus is out of service.

Transient Stability: Added additional validation checking on the EXWTGE model for values of XIQmax and XIQmin to catch values of 0.0 which indicate they should be set to default values of 1.45 and 0.5.

December 11, 2015

Features and Improvements

PV and QV Curve (PVQV) Tool: When opening the QV Curves dialog, the columns being shown in the Bus tab are processed. If the column "Selected" is in the list and the column "QVSelected" is NOT in the list, then the Selected Column is replaced with "QVSelected". In Version 18, we changed QV curves so that only buses that are flagged as QVSelected=YES are processed. In Version 17 and earlier we used the field Selected=YES. As a result, older PWB files may exist which have the Selected column in this table causing confusion. This change will avoid this confusion.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed bug when loading interface elements from an AUX file when the keywords for "BRANCH" etc.. used lowercase characters. In some locations it was not properly reading the interface elements.

Auxiliary Files (SCRIPT and DATA Sections): Store Line Tap by default with Transformer data. This had only been stored with Branch data and might be needed if the fixed taps are anything other than 1. Reordered the priority fields for the transformer nominal kV, fixed taps, and actual tap so that hopefully we end up with the correct actual tap after loading an aux file.

File Formats: Fixed bug when appending PWB cases and the same substation exists in both cases.

PV and QV Curve (PVQV) Tool: Fixed bug with ramping PV transfer in which the source contains the system slack. The slack would not actually move and could reach a situation in which no ramping is actually being done even though the tool looks like it keeps increasing the transfer.

December 7, 2015

Bug Fixes

Transient Stability: Added initial limit violation checking on the CSVGN5, CSVGN6, BPASVC, SVCWSC, and VWSCC models if the BSVS is outside the Bmax and Bmin input parameters. Also modified checking to ensure the Bpmax >= Bmax and Bpmin <= Bmin for these models.

Transient Stability: Modified so that when the CDC4T, CDC6T, CDC6, EPCDC dc tranmission line models have a minimum current specified and that minimum current is higher than the initial operating current of the DC line, then the transient stability DC line model will ignore the minimum current and treat it as the initial operating current instead.

Transient Stability: Fixed initialization of the WT3P1 model when ThetaMin was negative.

Transient Stability: Modified the WT3P1 model so that the absolute value of PiRat is used. Previously negative values of PiRat caused the model to be unstable.

Transient Stability: Modified validation checking on the PlayInRef model to ensure that the signal index values Pref_Index and Vref_Index are not beyond the number of signals available in the referenced playin model.

Transient Stability: When saving transient stability model to an AUX file, the LTC1 models were not being stored. This has been fixed.

Transient Stability: Modified storage of the Rotor Angle for generator models. This field was storing a value even for non-synchronous machines which was confusing. The Rotor Angle in results will now always be stored as 0.0 for any generator which is not either a synchronous machine, PLAYINGEN, InfiniteBusSignalGen, WT3G1, or WT3G2. (The wind turbines have a PLL state that is a useful field to track similar to a rotor angle)

User Interface Dialogs: Modified pop-up menu in log to show a checkbox beside "Show Time Stamp" rather than changing caption from "Disable Time Stamp" to "Enable Time Stamp". Also fixed a bug where that change wasn't happening at all.

December 1, 2015

Bug Fixes

File Formats: Changed the caption of the dialog that appears when loading an *.mon file from the limit group case information display. It now says
"Would you like to reset all Bus, Branch, and Interface Monitor Fields to YES?" which accurately reflects what it means. Also, it will now always load the *.mon file even if you click NO in response to this dialog. Previously it would not load the MON file if you chose No.

Transient Stability: When using the script command TSSolveAll(Yes) to run a Distributed Transient Stability simulation of many multiple contingencies, the transient stability results were not being properly returned. This has been fixed.

November 30, 2015

Features and Improvements

Case Information Displays: Modified the way left-clicking on column headings works for both sorting and reordering columns. Previously to reorder columns by dragging column headings you were required to hold down the Ctrl key before clicking with the left mouse button. Previously for sorting, columns were sorted immediately on the left mouse-DOWN. This worked just fine, but many users were not aware of the need to hold down the Ctrl key to reorder columns so this feature was largely unknown. It has now been changed as follows.

1. Left-click and dragging the mouse button will always reorder columns regardless of whether the Ctrl, Shift, or Alt keys
2. Sorting will now occur on the Mouse-UP instead of immediately upon Mouse-DOWN.
(This is done so that Simulator can first figure out if column headings are being dragged or not)
2a. If you did NOT drag and move any columns, then on Mouse-UP we will perform the sorting of the column
2b. If you did drag and move some columns, then on Mouse-UP and will complete the reorder of columns

Bug Fixes

File Formats: Modified reading of the MON file to properly handle reading MONITOR BRANCH lines which have a comment at the end of the line of text. Previously this was causing the lines to not be read in.

File Formats: fixed error with writing out multi-terminal DC Converter records to the EPC version 19 format. It was writing an extra double quotation mark which was causing an error in the file format.

Transient Stability: added support to the Distribution Equivalent for using the Rcomp and Xcomp line drop compensation values. Previously these were ignored.

November 24, 2015

Features and Improvements

PV and QV Curve (PVQV) Tool: @CASENAME, @CTGNAME, and @CTGMEMO will now work as special keywords in the title block for PV plots in a similar manner to the Transient Stability Plots.

User Interface Dialogs: Adding a new global transient stability option for "Minimum Voltage For Frequency Relay". When the per unit voltage is below this threshold then all frequency relays will treat their measured frequency as nominal frequency. This was done to mimic the voltage inhibit flag of real relay models and also to prevent motors stuck behind a fault from tripping on low frequency when the measured frequency behind the fault is suspect.

Bug Fixes

File Formats: When writing out shunt data to an EPC file, we had been writing -1 for the bus number of the controlling shunt when there was no controlling shunt. Now we are writing 0.

File Formats: Added svc important fields needed when saving case as an entire case to an aux file.

Transient Stability: Adding in support for transformer tap switching in the distribution equivalent model and in the CMPLDW model. Previously this was being ignored.

November 16, 2015

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed error when writing out InjectionGroup objects to an AUX file when using a SUBDATA section to write the PartPoint objects AND when writing using labels. We were not properly writing out the label identifier of the objects in the PartPoint.

Distributed Computation: When running TSSolveAll with Distributed enabled, the script call now blocks until the TS run is completed.

Transient Stability: REEC_A, REEC_B, and REEC_C models were not accepting a power input from the PlayInRef model. This has been fixed.

November 6, 2015

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added optional parameter filter to the end of SetSensitivitiesAtOutOfServiceClosest and CalculateTLR script commands to specify a bus filter for the out of service buses that should have their sensitivities set.

Contingency Analysis Tool: Contingency Limit Violation results including the Value, Limit, and Percent whill show at least 4 significant digits regardless of the decimal places specified by the user.

Bug Fixes

Transient Stability: When using the Scaled Quadratic Saturation Model for an exciter model, if a value of E1=0 we now automatically ignore the saturation function. The saturation function is B*(E-A)^2/E so if E=0 this function is undefined so this input data does not make sense.

November 3, 2015

Bug Fixes

Fault Analysis: Fixed a bug when using Pre-fault profiles of IEC-909 or Flat Classical. The internal voltage of generators was always being calculated using the solved power flow bus voltages, when the internal voltages should instead have been set to the IEC-909 voltage or flat start voltage, respectively.

File Formats: Labels were not being assigned to Switched Shunt records when reading hdbexport file. This has been fixed.

General: Fixed error in editing the "Enforce Current Limit" field for a MTDCConverter through a case information display or auxiliary file.

Power Flow Solution: Fixed calculation of the transformer sensitivity when using line drop compensation control on a transformer. It was not properly taking into account the effect of changing the tap on PQ flows on the transformer and propogating this sensitivity to the controlled point.

Sensitivity Calculations: On the Line Loading Replicator dialog, the Selected field in the injection change grid now goes to the element in the grid and not the grid object itself. The Object ID field has been added to allow identification of the element by any key field.

Transient Stability: Added hard-coded minimum values of the following for use in a transient stability simulation.
0.3 for Minimum Per Unit Voltage for Constant Power Loads
0.2 for Minimum Per Unit Voltage for Constant Current Loads
If input values are below these thresholds, Simulator will include a validation warning indicating that we will assume values equal to these threshold.

Transient Stability: When using the option to only include generic limit monitors for synchronous generators without relay models, relay models will not be considered unless they are active. GP2 relays will always be ignored in this check.

October 26, 2015

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Modified reading the BusSlack field of an Area and the Voltage Controlling Converter Bus for a multi-terminal DC line so that they can also read the bus by label.

General: Evaluating Model Expressions that are interlinked could become very slow. This will make it impossible to view the expressions or do any calculations with them like contingency analysis, ATC, PV, and QV. This evaluation process has been sped up.

General: A change was made in the September 23, 2015 patch to AND and OR operators in Expressions and Model Expressions that could cause them not to evaluate correctly. This has been fixed.

Transient Stability: Fixed error when writing out REGC_A models to the DYD file format. The following values are now always written Khv = 0.7 and qmin = -1.3. These values are not used by PowerWorld Simulator and these represent typical used (nearly universally used) value in DYD files.

Transient Stability: Modified REGC_A to contain Khv and Qlim parameters. These parameters are NOT used by PowerWorld Simulator, but they are part of the DYD file so we read and maintain them for users with DYD files to avoid confusion.

Transient Stability: Modified the REGC_A to contain an Xe parameter to represent generator effective reactance in per unit. If this value is zero then we will divide the value Iq by this amount and also model an impedance of (jXe) at the bus in the network boundary equations. This mimics what is done for WT3G type 3 wind turbines.

October 21, 2015

Features and Improvements

Transient Stability: Modified loading of DYR files to look for particular user-written models commonly used in ERCOT and MMWG cases which represent wind turbine models.
* USRMDLs W4G2U and SWTGU1 are both converted to WT4G1.
* USRMDL VTGTPA is converted to VTGTPAT
* USRMDL VTGDCA is converted to VTGDCAT
* USRMDL FRQTPA is converted to FRQTPAT
* USRMDL FRQDCA is converted to FRQDCAT
* USRMDL which are part of the GEWTG1/GEWTE1/GEWTT/WGUSTC/GEWTA/GEWTP/GEWTPT suite of user-written models are automatically converted to WT3G2/WT3E1/WT3T1/WT3P1. (This suite of models is seen in ERCOT cases.)
* USRMDL which are part of the GEWTG2/GEWTE2/GEWTT1/GEWTP2/GEWGD1/GEWTA2/GEWPLT2 suite of user-written models are automatically converted to WT3G2/WT3E1/WT3T1/WT3P1. (This suite of models is seen in MMWG cases.)

Transient Stability: Many renewable energy machine models feed a commanded Ip and Iq through a small time delay with the output then feeding into the network boundary equations as the real and reactive current injections. We have added parameter checking to ensure that these time delays are no larger than 0.20 seconds. If the time delay is larger than 0.2 seconds then it will be treated as 0.2 seconds. In the 1000s of models like these we have seen, these time delay values are on the order of 0.02 seconds, but we were seeing a case with a value of 1.0 second which creates an unstable model. This effects the following models presently: WT3G, WT3G1, WT3G2, WT4G, WT4G1, REGC_A, PVD1.

Transient Stability: Improved messages written to the log when encountering user-written model in the DYR file.

Transient Stability: When reading DYR files, added support for reading a USRMDL/GENROA model. This is a user-written model commonly used in NY-ISO in North America which simply copies the input parameters for GENROU from another GENROU model.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): In the TapTransmissionLine script command the first bus entered is now the nearbus and this will be used as the reference for the PosAlongLine. Previously, we were always using the frombus of the line as the reference.

Contingency Analysis: Fixed error with loading in variable name references when Model Expressions refer to another model expression when using the WECC RAS format

October 19, 2015

Features and Improvements

Transient Stability: Added FRQDCAT/FRQTPAT and VTGDCAT/VTGTPAT transient models and the entire support for allowing multiple instances of the same relay in the gens others models.

Transient Stability: Modified the treatment of the LD1PAC model in the algebraic network boundary equations when LD1PAC is not stalled. It was possible for the LD1PAC model to cause a voltage collapse when operating in the "running state 2" portion of the curve. We have modified the algebraic equations to relax this equation to make it less likely for this to occur.

Bug Fixes

Security Constrained OPF (SCOPF) Tool: When using the DC power flow it was not possible to choose to abort the solution of the SCOPF. This has been fixed so that the Abort button can be clicked to abort the solution.

Transient Stability: When storing bus results to RAM any loads which included a Distribution Equivalent were not properly saving the MW/Mvar values for the BUS.

October 13, 2015

Features and Improvements

Oneline Diagrams: Added ability to save out Dynamic Formatting defined for a specific oneline to an AXD file.

Bug Fixes

File Formats: When loading a PWB file, the message log will indicate that we are "Validating Case". This is the point at which things such as a topology check on the system to verify slack buses are defined is done. Previously this validation was done BEFORE we had actually read the case option indicating if slack buses can be dynamically added/removed. As a result, if the PWB case had been saved to NOT allow this, during an interim point in reading the PWB slack buses would created and viable islands would be created. However immediately after doing this, the option would be read indicating that slack buses should not be dynamically created. Simulator would properly remove the slack buses as soon as the user did something to cause a topology check to occur (such as solving the case or even just looking at the list of islands). However, until this happened the various case information displays may show additional viable islands and thus different amounts of MW and Mvar injections as well. This interim situation with the extra slacks was causing confusion. We have fixed this by simply doing the "Case Validation" AFTER reading the option regarding slacks.

Transient Stability: Fixed bug that occurred when modeling a two-terminal DC line which included a stability model and had the DC line on constant current control.

Transient Stability: Modified EXAC1 which have derivative feedback and very small time constant (Tf) so that the subinterval integrations would start at 32 subintervals instead of 16. This helps ensure numerical stability of the algorithms

Transient Stability: Fixed error in initialization of the measured voltage of WT3E and WT3E1 when Kiv=0.

Transient Stability: Fixed error in implementation of the PTIST1 and PTIST3 model related to the filter block (T1, T2, T3, and T4)

October 8, 2015

Features and Improvements

Transient Stability: Added option with a SubPlot regarding whether to show the legend. "YES" means always show legend. "No" means never show legend. "Default" means show the legend if the number of plot series is below the global threshold specified on the plot tab of the Plot Designer. The default behavior is "Default" which matches the previous hardcoded feature.

Transient Stability: Modified the network boundary equation treatment of the svsmo3 switched shunt model for modeling SVCs. All other switched shunt models (including svsmo1 and svsmo2) are modeled as an impedance in the network equations. The svsmo3 however is now handled internally in PowerWorld Simulator as a constant current injection instead. This matches the treatment used for various generator machine models such as wt3g, wt4g, regc_a, pvd1, etc.

Bug Fixes

Transient Stability: Fixed an error with handling the non-windup limits on PI loops in the svsmo1, svsmo2, and svsmo3 models.

October 7, 2015

Features and Improvements

Case Information Displays: When saving to a CSV file from a case information display, now have the option to save using Variable Names or Column Headers.

Contingency Analysis Tool: modified so that Version 18 can properly read contingency actions that refer to expression and fields using a string that contains the special or tags. This will be the new convention used in Version 19 always.

File Formats: Added code when reading OTG format files that will look for the keyword "newbase" in the file, and treat the rest of the contingencies in the file as n-1-1 contingencies that get combined with the first contingency read after the newbase keyword, until another newbase keyword is encountered to signify the base contingency will change from that point to the next newbase.

Bug Fixes

Contingency Analysis: Fixed potential bug with not writing DC Line contingency actions to file versions less than version 18.

Transient Stability: For the CMPLDW and CMPLDWNF model only, there was an error when using SimAuto or the Export Case Object Fields to dump out a list of available fields for the CMPLDW and CMPLDWNF models. The MotorA, B, C, D parameters were missing. This has been fixed.

Transient Stability: When saving or printing a plot that includes a Title Block, any Left or Right memo text may not have appeared with the correct carriage returns. This has been fixed.

Transient Stability: Fixed problem with reading the repc_a model from a DYD file when specifying the branch and monitored bus.

Transient Stability: Fixed error with how the CLOD model was being initialized.

September 23, 2015

Bug Fixes

Contingency Analysis: SolvePowerFlow actions were causing actions with non-zero time delays to not be applied correctly. This has been fixed.

Oneline Diagrams: Fixed a bug where two breakers were auto-inserted on top of one another; also revised breaker placement on bus ties to prevent single breakers from being placed in the center of the tie if a pie chart is being inserted there as well.

Security Constrained OPF (SCOPF) Tool: The contingency option to solve an OPF after each contingency is now ignored when running contingency analysis as part of the SCOPF.

User Interface Dialogs: The substation filter was not included when saving the Auto Insert Contingency options to an auxiliary file from the dialog. This has been fixed.

September 17, 2015

Features and Improvements

Sensitivity Calculations: Interfaces can now be monitored with the LODF Matrix tool.

Bug Fixes

Contingency Analysis: Fixed an access violation that could occur when closing Simulator. This was due to a RAS element containing an Inclusion Filter.

Distributed Computation: In some situations, a distributed computing run may hang at completion. This has been fixed.

File Formats: 1. Added button to clear hdbexport cbtype mapping table.
2. Updated hdbexport file parser so that it will use the TYPE_CB record to set the cb type when it's available (rather than following the P__CBTYP and using the information on the CBTYP records).

Power Flow Solution: Made a correction to SVSMO2 SVC model to use a look-up table with all of the possible combinations of B MVARS to determine the B output to the closest step.

September 11, 2015

Features and Improvements

File Formats: For the hdbexport file reader, the changes made to support reverse direction pointers on August 20, 2015 introduced a bug in reading the impedance correction tables values (which use the TABVAL/TABPT/TAB records). This was resulting in the impedance correction factors being off by a factor of 100. This has been fixed.

September 9, 2015

Features and Improvements

Transient Stability: When saving transient stability settings to an auxiliary file, the dialog that allows you to select what to save has been modified. There is now an option that allows you to Save Transient Limit Monitors.

Bug Fixes

File Formats: If using the option to Append a Case with an EPC file with Options, the dialog was not properly allowing you to specify an EPC version. It was interpreting the selected version as one less than selected, meaning that a version 18 file was read as a version 17 file. This could result in information that was added at the end of records for version 18 not being read correctly. This has been fixed.

Power Flow Solution: Fixed a bug with how a SVC of type SVSMO2 operates when there is non-zero compensating reactance.

Power Flow Solution: SVC of type SVSMO2 previously would not move if the same High and Low voltage regulation settings were specified. This has been fixed.

Power Flow Solution: Fixed some problems with slow control for SVC type SVSMO2.

Transient Stability: Fixed a bug with the SVSMO3 model.

User Interface Dialogs: Fixed the advanced/quick filter dialog so that when using the keyboard to select the variablename a correct variable would be chosen.

User Interface Dialogs: When editing a Model Expression on the Model Expression dialog, after defining a new variable the expression function would always reset back to the function that existed when the dialog was opened. This would occur even if you had just changed that function. This has been fixed.

August 28, 2015

Features and Improvements

Sensitivity Calculations: Added the ability to store the display/column option settings for the grids on the Flows and Voltages Sensitivities dialog under the "Self Sensitivity" and the "Multiple Meters, Single Control Change" tabs. Previously these could be modified but after closing the dialog and reopening it, Simulator would not maintain display/column options on those.

Transient Stability: Added support for reading the REEC_C model from a DYD file.

Transient Stability: Modified the Validation message about treating generators with no machine model as negative load to make it clear that we treat the generator as constant current in this situation.

Transient Stability: Modified to bring the transient stability dialog back up in multiple contingency mode if it was in that mode the last time the user open the dialog.

User Interface Dialogs: Modified the Recent Cases list so that the file extension is included.
Also now include the file path in situations that duplicate entries are shown in the Recent Cases List (This can occur with the same file name, but different file path).

Bug Fixes

File Formats: Fixed an error reading in a PWB file if there were any Model Conditions referencing three-winding transformers when the file was saved.

Oneline Diagrams: Fixed bug in applying oneline emphasis filter.

Oneline Diagrams: Fixed a bug with properly drawing dashed lines while in Run Mode.

Oneline Diagrams: Additional modifications to prevent any dialog boxes or onelines from being dragged to a part of the screen that will prevent the user from clicking on the title bar of a form such that they can't move it again.

Power Flow Solution: Improved DC line tap calculations to avoid controller oscillations in the power flow solution.

Transient Stability: Fixed access violation that could result during the initialization of a case containing Load Distribution Equivalent records.

Transient Stability: Fixed a bug with auto-correcting the Xc value for SVCs. It was setting the value to 0 if the user selected to Auto-Correct the values in the validation dialog.

August 20, 2015

Features and Improvements

Contingency Analysis Tool: Contingency violations can now access the Monitor field for their elements so that this can be set directly from the contingency results instead of going to the Limit Monitoring Settings.

Added support for PRIO field on CP records (putting it in the VarRegulationSharing property).
Added support pointers in either direction from XFs to PSs or PSs to XFs.

Bug Fixes

File Formats: A log warning message is written if duplicate generators are encountered when reading a RAW file.

File Formats: Made some WECC Switch file changes:
1. Parse fault impedance with FB record
2. Use OPEN BOTH action when parsing FL record that opens both ends of the line at the same time
3. Use solid fault if impedance values are all 0.0

August 12, 2015

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added new script command CTGClearAllResults that does what the name implies. This does the same thing as the Other > Clear All Contingency Results button on the contingency analysis dialog.

Transient Stability: Fixed error in reporting with a BUS record what the total load was at the bus if it contained a distribution equivalent.

Transient Stability: Fixed an error that could cause a network solution failure when closing back in a disconnected island during a transient stability simulation. This error would not always occur, but could sometimes.

August 3, 2015

Features and Improvements

Transient Stability: Added MEXS Exciter model.

User Interface Dialogs: On the Scale dialog, hitting Enter after changing a number would sometimes trigger the scaling instead of just changing the value to be used in the scaling. This should no longer happen.

Bug Fixes

File Formats: Fixed error when reading in the ##R records from a UCTE file. If the du% value for a phase shifter was negative we were not properly reading the phase shifter. This has now been fixed.

Transient Stability: Modified the transient stability dialog so that if you load an AUX file or in any way edit the list of transient contingencies it will automatically rebuild the drop-down showing the list of transient contingencies. Previous this drop-down was maintained if you modified the transient contingency list by interacting with the Transient Stability Dialog itself. The drop-down will now also be properly maintained even when you Add, Delete, or Rename transient contingencies in any other manner (such as loading an AUX file from the file menu.)

July 30, 2015

Features and Improvements

Case Information Displays: Added 4 new fields to a BRANCH object.
"Open Ended/Charging Amps at From Bus" = Assuming the closed end of the branch is operating at 1.0 per unit voltage, this is the charging amps seen at the closed end of the branch when the branch is open at the From bus
"Open Ended/Charging Amps at To Bus" = Assuming the closed end of the branch is operating at 1.0 per unit voltage, this is the charging amps seen at the closed end of the branch when the branch is open at the To bus
"Open Ended/Per Unit Magnitude at From Bus" = Assuming the closed end of the branch is operating at 1.0 per unit voltage, this is the per unit voltage seen at the open end of the branch when the branch is open at the From Bus
"Open Ended/Per Unit Magnitude at To Bus" = Assuming the closed end of the branch is operating at 1.0 per unit voltage, this is the per unit voltage seen at the open end of the branch when the branch is open at the To Bus

Transient Stability: On the Transient Stability Dialog, we were finding that the button on the Result Storage page called "Load from Hard Drive File into RAM results specified by Store to RAM Options" was causing confusion. Users were assuming that in order to plot results or use the Transient Contour Toolbar that results must first be loaded into RAM. This has never been the case as these features simply obtain data directly from the TSR file without requiring you to load results into RAM. The same button is available at the bottom of the "Results from RAMTime Values" and in practice the only place that you see these results from RAM is on this page. To avoid continued user confusion, we have removed the button from the Result Storage tab and it is now only available on the Time Values page.

Transient Stability: When loading in transient stability data from an AUX, DYD, or DYR file, Simulator would prompt you asking "Do you want to clear the existing transient stability data first?". Feedback from many users was they would NEVER want to do this and it was a dangerous dialog to continually show users. We have removed this prompt and the clearing of stability data when loading a file.

If a user still wants to delete all stability models from their case, this can still be done under the AddOns ribbon tab under the drop down Stability Case InfoClear All Transient Stability Data.

Transient Stability: In the Transient Stability dialog, modified the drop-down showing all the transient contingencies in the so that the strings also show the categories of the contingency (if any categories have been assigned)

In the Transient Stability dialog, added a Find button next to the drop-down showing all the transient contingencies. The Find button allows you to find by either
1. Name of the Transient Contingency
2. Find the first transient contingency that has a transient contingency element that acts on a generator, load, bus, or switched shunt.

Bug Fixes

Contingency Analysis: Improved the processing complex contingencies which involve several POSTCHECK iterations to ensure that large generation changes are handled efficiently.

File Formats: More changes to reading the Min/Max phase shift values from a UCTE file format to ensure that the Max value is the positive one and the Min value is the negative phase.

File Formats: Fixed error in how Generator records were being read from the UN records in an hdbexport file.

File Formats: Fixed error in loading in RAW file which contained an VSC DC Line if the remotely regulated bus was not specified.

File Formats: When reading in a 2-winding transformer in a RAW file, the cosmetic storage of the Fixed Tap ratio on the to-bus side was not being done properly when the flag CZ=2 and when the nominal kV of the secondary winding was different than the nominal kV of the bus. This has been fixed so that you can see the values on the transformer base correctly inside Simulator. Note, this did not effect the solution as we were still converting and storing everything in Simulator on the System MVA base correctly. This only effecting viewing input data on the transformer base.

General: When saving a case it is possible to configure Simulator bring up a dialog asking you to add a comment to the case. It is also possible to configure Simulator to automatically save a case every so many minutes. This was bringing up the case comment form constantly. The Auto-Save feature has been changed to never show the case comment box.

Power Flow Solution: Made a change to how the Mvar limits are enforced by switched shunts operating as SVCs.

Transient Stability: modified how error messages are reported when we write out a model which can not be found in the case when reading a DYD file so that the error messages work when the DYD file contains labels as well.

Transient Stability: For a GENTPF/GENTPJ model when setting Tdopp or Tqopp to 0.0, this indicates that a transient model should be used for the generation model. The model should then be configured such that Xdpp=Xdp and Xqpp=Xqp=Xq to function appropriately. If the model was not setup this way from the start, then Simulator will change the parameter inside the simulation automatically to be treated in this manner. There was a bug however such that this wasn't properly handled which could cause generation to initialize incorrectly. This was occurring at the LITFAL generation in a WECC case. Simulator will now properly handle this without user-intervention.

Transient Stability: For GENTPF/GENTPJ models which had Tqop=0 to indicate special handling of a salient pole machine with a single amortisseur winding, we were not performing any validation checks on the magnitude of Xqpp relative to Xdpp. As a result, invalid data such as Xqpp=0 was not being flagged as an error and was not being auto-corrected. We now perform the same check on Xqpp as we do for all other GENTPF/GENTPJ model and thus if the value is very small (Xqpp<0.01*Xdpp, basically zero) then we set Xqpp=Xdpp.

July 20, 2015

Features and Improvements

Contingency Analysis Tool: Added ability of Limit Violations to show the Custom Float, Integer, and String fields associated with the overloaded object. This is available on both of the following tables:
1. Table showing the violations for only one contingency (on Contingency tab of dialog)
2. Table showing all contingency violations (on Results tab of dialog)

File Formats: Modified reading the "Promod" format for defining interfaces so that we look for the keyword "BASECASE" and treat it the same as "BASE" was treated before.

Transient Stability: Added additional features to the "Insert Apply and Clear Fault" button on the transient stability dialog. Previously when doing this we did the following:
Branch fault: create 3 events: Fault, OpenFrom, and OpenTo
Bus Fault: create 2 events: Fault, ClearFault
We have now modified it so that the user may choose whether to "Clear Fault" or "Open" for the extra events.
Note: The auto-insert transient contingency tool will always do OPEN for all extra events.

Transient Stability: modified the REEC_A, REEC_B, and REEC_C models so that when pfflag = 1 (constant power factor), then we initialize Qext to 0.0.
It really doesn't matter in this particular situation because Qext isn't used if pfflag = 1, but it is less confusing when connected to an REPC_A model if it defaults to zero in this situation.

User Interface Dialogs: Added menu options for Append Case to directly access the different file types from the dropdown menu.

Bug Fixes

Contingency Analysis: Fixed access violation that could occur when viewing contingency elements for actions involving gens, loads, or shunts but the action is defined with the bus instead of the specific object.

File Formats: When reading a UCTE file, modified how the tap ratios were begin calculated from the ##R records in a UCTE file. Previously for tap ratios, if the ##T record "Rated Voltage 1" and "Rated Voltage 2" did not match the terminal bus nominal voltages, then the tap ratios being read were not handle quite correct.

The Simulator "Tap Ratio" column shows the tap ratio converted to the system base, while the UCTE file tap ratios described in the ##R records are the transformer base voltages. These were not being properly scaled when reading the ##R record. Also keep this mind if you compare the tap ratios you calculated in the UCTE file to those shown in Simulator. When doing this comparison you need to keep two things in mind:
1. Simulator always assumes the variable tap is on the FROM bus side of the transformer. The UCTE file assume it is always on the TO bus side, so that tap ratios will be the reciprocal of one another.
2. Ratios will only match if you compare the "Transformer BaseTap Ratio" value in Simulator which shows the tap ratio of the transformer on the transformer base instead of the system base.

File Formats: When reading a UCTE file, added ability to read the phase angle shift values from the ##R records. Previously they were being ignored and all phase shifts were being set to zero. One important note when comparing angles you see in Simulator. Simulator always assumes the variable phase is on the FROM bus side of the transformer while the UCTE file assumes it is always on the TO side, so the angles read in Simulator will have the opposite sign convention.

File Formats: Fix a bug that was preventing the opening of some cases when the slack bus of an area did not belong to the area to which the bus belonged. Simulator ignores this specification when it is not consistent, but an access violation was occurring related to writing this warning message out to the log.

Oneline Diagrams: Various fixes with the Geo Data View features.

Simulator Automation Server (SimAuto): When closing an instance of Simulator using SimAuto, previously the various options in Simulator which are normally stored to the Windows registry were not stored. This includes settings like Distributed Computing and Keyboard shortcuts, but other things as well. Now when closing an instance of Simulator in SimAuto the behavior will be the same as though you closed from the traditional graphical interface.

Transient Stability: fixed an error in with loading older version 16 PWB files which store transient stability contingency results. This will only occur when loading version 16 files into Version 17 or 18. This new patch will load these older files correctly now.

Transient Stability: Made changes to LHFRT way of handling the user input data. They frequency deviation are given in Hz but were previously being interpreted as per unit.

Transient Stability: Fixed reporting of a limit violation on GPWSCC model when Ki = 0. It was reporting a limit violation even though the state was ignored.

Transient Stability: When checking a limit against a min/max limit pair, sometimes Simulator would report a state violation even when the value was exactly at the limit. It will now only report limit violations to the user if they exceed the limit by more than 0.01% of the limit. Thus if the max limit is 1.0000 then it will only report a limit violation if it's 1.0001 or higher. Note, this ONLY effects the reporting of limit to the user. The value is still pegged at the limit, but we just don't report state limit violations that are likely due to numerical precision.

Transient Stability: Fixed various column headings in transient stability models which were not unique. This will only effect you if you were creating stability models by copying and pasting from Excel. Otherwise these are purely cosmetic bug fixes.

July 2, 2015

Features and Improvements

Transient Stability: Modified the validation check on synchronous machines to ensure that Xqpp is not too big. Previously we enforced (Xqpp <= 1.1Xdpp), but have changed this to (Xqpp <= 1.5*Xdpp).

Bug Fixes

Available Transfer Capability (ATC) Tool: Fixed bug introduced in the June 18 patch when reading the concise WECC RAS format that contained Model Expressions. The field for "Expression" was not being properly read.

June 30, 2015

Features and Improvements

Transient Stability: Modification were made when transferring results from transient stability for viewing inside Simulator.
1. The situation where one end of a transmission line is open is now handled by putting in a fictitious bus shunt so that mismatches which are viewed are meaningful.
2. We now show islands that exist in stability which would not be permitted to exist in the power flow, such as an island without any load or an island with only 1 bus.

Bug Fixes

Fault Analysis: When applying a single-line to ground fault to a portion of the system that has no zero sequence path to ground, Simulator was not correctly calculating the zero sequence Thevenin impedance (which should have been infinite!). This situation is highly unusual in a real system (as grounding is quite important), but the software will now appropriately return a fault current of zero.

Transient Stability: Changed the DC line algebraic equation solution in transient stability. Previously when using algebraic models of the DC network (no model, EPCDC, CDC6, etc...) during the network boundary equation solution, after each Newton iteration, the firing angles would be recalculated to attempt to exactly set the desired Current (or Power) of the DC converters. For algebraic solutions near points where firing angle limits were either hit or backed off, this could make the network boundary solution oscillate and fail. Attempting to get the current/power setting exact is unnecessary though. Instead, we now only modify the firing angle at the beginning of each time step in the simulation and then leave the firing angle constant. This is the same process that is done when actually modeling the dynamics of the DC network and using a transient stability model for the DC converters. Essentially the new algebraic solution is assuming that the firing angle is calculated based on the last time step's AC voltage profile and thus essentially the firing angle control has a 1 time-step delay. This is perfectly appropriate and makes the network boundary solution much more robust and the current/power control is still met exactly withing a couple time steps.

June 25, 2015

Features and Improvements

File Formats: When reading an EPC file, a generator Mvar output that is within 0.1% of the Minimum Mvar or Maximum Mvar output will now be initialized to assume that the generator is stuck at it's min/max Mvar limit (it will be initialized to a PQ bus instead of a PV bus). Consider an example generator set at 29.98 Mvar which has MvarMin = -20.00 and MvarMax = 30.00. This means that it is within 0.04% of it's upper limit: (30 - 29.98)/(30 - (-20))*100. When Simulator reads this we will assume the generator is stuck at it's maximum Mvar limit and we will change the value to 30.00 instead.

Transient Stability: Changed validation for REEC_A, REEC_B, and REEC_C so that when Pfflag = 1 we no longer report as an error if Qflag = 1. This is now simply reported as a warning indicating that this is a possible configuration, though not a typical one.

Transient Stability: Modified the synchronous generator (GENROU, GENSAL, GENTPF, GENTPJ, etc.) validation so that we allow Xl=Xdpp or Xl=Xqpp. We also added a check to enforce that Xl < Xdp and Xl < Xqp.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): When loading a text file format (such as RAW or EPC file) if the file has only line feeds and not carriage returns, then a dialog appears asking if you'd like to fix the file. When loading a case from a script command however, this dialog is not wanted so we will now automatically assume that the file should be converted to Carriage Return/Line Feed pairs

June 18, 2015

Bug Fixes

Case Information Displays: Made some changes to impedance correction table fields with a transformer. Now have two fields: Correction Table Used and Correction Table Specified. The Used value might be different than the Specified value if the table that the user specifies cannot be found. If the user changes either of these fields as input to a case information display or through an auxiliary file, the Specified value will change. This should allow the retention of what the user specified but still notify if that table cannot be used. This will allow transformers to keep their impedance correction table settings if they are set prior to the impedance correction tables themselves actually being created.

File Formats: When writing out contingency containing any section of a multi-section line in the PTI CON format, write out the from bus, to bus, and circuit of the multi-section line rather than the section.

General: On the Scale dialog, maximum New Value fields were limited to abs(9999). This has been increased.

Transient Stability: Fixed a bug that was causing multiple events to occur for the same under voltage motor trip.

June 11, 2015

Features and Improvements

Retriever: Added a folder for the field list to the Alarm information for Areas, Zones, and Substations.

Retriever: Added complete support to SuperAreas for the Alarm informational fields.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Made some changes to how the user-specified extra headers and values are read when using the SaveDataWithExtra script command. Any strings enclosed in double quotes will be stripped of the enclosers. Any strings containing double double quotes will have them replaced with single double quotes. The input should be formatted in a manner to indicate how it should be written to the CSV.

File Formats: Fixed an access violation that could occur when appending a PWB file.

File Formats: When loading three-winding transformers from a PTI CON file, all three winding buses must be specified. If not, there is an error and the contingency element will be unlinked.

File Formats: When loading unlinked elements from a PTI CON file, keep the unlinked element with the contingency definition. This will NOT be able to be relinked, but a record of the error will exist.

June 9, 2015

Features and Improvements

Case Information Displays: Added new Injection Group fields to show the "Number of Gens Online", "Number of Loads Online", and "Number of Shunts Online".

File Formats: Added special parsing when reading text descriptions of a branch to recognize special versions for an individual winding of a three-winding transformer or an individual section of a multi-section line. This is done when reading:
1. INTERFACEELEMENT objects or when reading
2. Various objects that refer to a specific object (Model Condition, Model Expressions, Custom Monitor, etc.)
3. ObjectID of a BRANCH
Normally a branch is identified with the string "BRANCH num1 num2 ckt" or "BRANCH 'name_kv1' 'name_kv2', ckt".
For a multi-section line section we can now accept "BRANCH msnum1 msnum2 ckt sec" or "BRANCH 'msname_kv1' 'msname_kv2' ckt sec" where the msnum1 and msnum2 represent the terminal of the multi-section line aggregation and the sec represents which section of that aggregation to use.
For a three-winding transformer, we can now accept "BRANCH num1 num2 num3 ckt" or "BRANCH 'name_kv1' 'name_kv2' 'name_kv3' ckt" where the identifiers represent the three-winding transformer key fields, but we interpret this as the BRANCH which is attached to the first terminal listed (num1 or name_kv1).
Also note that when reading these special interpretations for an interface, the order of the multi-section line terminals will determine the direction being monitors and for three-winding transformer windings we will always monitor in the direction going into the transformer.

General: Three-winding transformers can now be used as part of Model Conditions and Model Expressions.

Transient Stability: Added ATRRELAY model.

Transient Stability: Added OOSMHO Line Relay Model.

Bug Fixes

General: Fixed bug when opening the Model Condition dialog if the class of the filter was different than the class of the object. This worked correctly on the dialog while defining the Model Condition, but when choosing Show Dialog on an existing model condition it was not properly populating the dialog.

Power Flow Solution: Made some corrections to the balancing of parallel transformer taps when the parallel transformers were defined in opposite directions in regards to the from and to buses.

PV and QV Curve (PVQV) Tool: Removed options from the Load button at the bottom of the QV dialog. There is no reason to load options and results separately and this was causing problems by skipping DATA sections necessary for the QV setup. Clicking the Load button now will load all contents of an auxiliary file.

June 4, 2015

Features and Improvements

Case Information Displays: Added new field to Switched Shunts, "Controlling SVC Object ID", that will allow identifying an SVC that controls a fixed shunt by any of the available key fields. Previously, the controlling SVC could only be identified by a bus number and shunt ID.

Contingency Analysis Tool: Modified the layout of the Contingency Definitions folder on the Options tab of the Contingency Dialog. Previously entries for All Contingency Elements, Remedial Actions, Contingency Blocks, Model Filters/Conditions/Expressions, etc. were all under one folder. They have now been split up into folders to make "Remedial Action Definitions" more prominent and also to add Contingency Blocks and Global Actions to a "Legacy Definitions" folder to discourage their future use.

Transient Stability: Expanded on the "Solved" field for a transient contingency. Previously this field said "YES" if the transient contingency had been been attempted at all regardless of whether it was successfully finished. There are now 3 fields:
1. Processed: This will say YES if the transient contingency solution was attempted
2. Solved: This will say YES only if the transient contingency solution was run and successfully finished
3. Reason Not Solved: When Solved = NO, this will be a string indicating why the solution was not finished

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Scale script command now allows you not to scale LOAD MW or Mvar while scaling the other value. The [parameters] entries can now be specified as NO. Scale(LOAD, MW, [-250, NO], AREA) will only scale MW and will not scale Mvar. Scale(LOAD, MW, [NO, -250], AREA) will only scale Mvar and will not scale MW.

Case Information Displays: Fixed the folder listing the multiple direction PTDF fields for the Branch object. These values were appearing under the folder for "LODF Multiple" in the field list and now correctly appear under the "PTDF Multiple" instead.

Contingency Analysis: Fixed bug when using contingency actions with non-zero time delays in a full-topology case using "Open with Breakers" or "Close with Breakers" actions. The actions with the non-zero time delays would never be implemented.

Contingency Analysis: Modified the caption on various tabs that said "Contingency Definition" and changed them to say simply "Definition". These same dialogs were used for Contingency Blocks Elements, Contingency Elements, and Remedial Action Elements and this caused confusion.

Contingency Analysis: Fixed a bug with Distributed Contingency Analysis caused by quote characters being part of contingency names. This bug would cause the results from distributed runs to not be processed correctly. This has been fixed.

Contingency Analysis: Fixed bugs with load throwover not being done correctly during a linear dc contingency calculation in which the load is thrown over to another bus that is also being disconnected during the contingency.

File Formats: Fixed a problem when opening a valid PWB file associated with a PWD file that cannot be opened. Previously, the case would be cleared. Now the case will remain open without a oneline diagram.

General: When creating an auxiliary file from the Aux Export Format Description tool, the file extension would not be set by default. This has been fixed.

General: Several bugs were fixed with the Scale tool:
(1) Generators could not be scaled to a New Value that was negative.
(2) Loads could not be scaled to a New Value that was negative using the Scale dialog because the dialog prevented entering a negative value.
(3) Script command now allows you not to scale LOAD MW or Mvar while scaling the other value. The [parameters] entries can now be specified as NO. Scale(LOAD, MW, [-250, NO], AREA) will only scale MW and will not scale Mvar. Scale(LOAD, MW, [NO, -250], AREA) will only scale Mvar and will not scale MW.
(4) Generators with a negative Original Value could not be scaled regardless of the scaling direction.

Power Flow Solution: If a generator's MinMW < MaxMW then it was possible for a generator on MW control in the power flow to oscillate between it's MinMW and MaxMW output. This has been fixed so that the generator will just not move instead of causing oscillations.

Sensitivity Calculations: Redo the injection group sensitivity calculations for TLR results after setting the sensitivities of out-of-service buses to the values of their closest in-service bus.

Transient Stability: Modified GENCLS so it sets its field current equal to the initial field voltage.

Transient Stability: When using filters, the Buses and Generators tabs on the Results from RAM --> Minimum/Maximum Values page were not indicating that a filter was applied. This has been fixed.

Transient Stability: Fixed error that was not showing the "Finished at XX.XXX seconds" text in the edit box showing the status of a transient contingency analysis run at the top of the Transient Stability dialog.

Transient Stability: Added scroll bars to the Control tab on the Simulation page of the Transient Stability dialog. This will allow access to the Simulation Time Values for varying screen resolutions.

May 19, 2015

Features and Improvements

File Formats: Added process to check the voltage magnitude and angle of star buses at the end of the RAW file read, and evaluate the mismatches at the three terminal buses of the three winding transformer. If we determine that our own estimate of what we think the voltage and angle should be at the star bus results in improved mismatches at the three terminal buses, we will apply our estimated voltage values to the star bus, otherwise we will keep the voltage magnitude and angle as read from the RAW file for the star bus.

Bug Fixes

File Formats: When reading the XF regulation parameters in a UCTE file, a bug existed such that the relevant transformers could not be found. This has been fixed so that the regulation parameters are correctly applied.

File Formats: The last line of a UCTE file was not being processed. This has been fixed.

PV and QV Curve (PVQV) Tool: Fixed access violation that could occur at the start of a PV run when using the interface ramping option.

PV and QV Curve (PVQV) Tool: When using the interface ramping option with the PV tool, do the full OPF solution always rather than trying to speed things up by doing only a single outer loop. This will ensure that the results are within the desired tolerance if a solution is found.

Transient Stability: Modified the DC Line calculation when considering mode 3. Mode 3 is the constant Beta mode which is used as a gradual transition between Mode 1 (full current) and Mode 2 (current reduced by the current margin). Mode 3 uses the Beta from the previous network solution which it had in a Mode 1 or 2 solution. Immediately after a network event however, Mode 3 can not use the Beta from the previous solution because the entire network state had a discrete change and the Beta from that solution is not reliably reasonable for the new network state. Doing so could lead to a solution failure. This has been fixed so that Mode 3 operation is not allow in the timestep immediately following a network event.

May 12, 2015

Bug Fixes

Transient Stability: Fixed error with reading the LHVRT and LHFRT from a DYD file. The last field Alarm was not marked as an optional field and thus any records that did not include the alarm field were skipped. This bug was introduced in March 20, 2015 patch.

May 8, 2015

Bug Fixes

File Formats: Modified the reading of a RAW file so that when a BusType = 4 is read we enforce that this bus is dead after reading the file. We were encountering RAW files with BusTypes that were NOT consistent with the line statuses that were contained in the RAW file. A bus would appear in PowerWorld Simulator to be in a viable and online island due to the fact that the bus was connected by CLOSED branches to online generation. In this situation clearly something is wrong with the consistency of the input data, and previously PowerWorld had obeyed the branch statuses instead of the BusType. This has been modified so that in this situation all branches that connect to the bus marked as BusType = 4 will be opened and an appropriate log message indicating the input file inconsistency will be written. Customers have indicated that this is appropriate treatment when reading a RAW file with inconsistent data.

GIC: When the GIC Transformer display is being viewed, if you saved the case, an nuisance access violation would occur. This didn't hurt anything and the case info just immediately refreshed, but this nuisance access violation has been fixed.

Integrated Topology Processing (ITP): When using the option to Apply Selected Contingency, actions involving breakers did not do anything because we were not expanding them into their actual breakers. This has been fixed.

Transient Stability: Fixed error in reading the LSDT3 model from a DYD file. Some of the columns were read in an incorrect order.

May 6, 2015

Features and Improvements

File Formats: Lshunt actions, which cause a line shunt to be opened or closed or have a new susceptance value, are now supported when reading the OTG format.

File Formats: Isolate actions, which cause a bus to be opened, are now supported when reading the OTG format.

General: ViolationCTG and LimitViol object types can now be filtered using secondary object filters.

Bug Fixes

Case Information Displays: When showing a list of Line Shunts associated with a particular line from a the Line Dialog, previously it was possible to have that list filtered by area/zone/owner or advanced filters. This never necessary as this list is very short and could cause confusion as it would hide a line shunt.

File Formats: Fixed bug with specifying a start bus number for three-winding transformer star buses when loading in a RAW or Auxiliary file. The bus numbers would not increment properly and the same bus number could be used multiple times.

File Formats: Fixed a problem with owners stored with EPC extra data for switched shunts storing too many owners and incorrectly writing out in the EPC file.

May 1, 2015

Features and Improvements

Case Information Displays: Added new fields with branches to show the from and to MW and Mvar flows calculated from voltages and also ignoring the branch status. Fields will contain "(Calculated from voltages ignoring status)" in their name. If either of the terminal buses is disconnected, nothing will be calculated.

Bug Fixes

File Formats: When reading a PTI CON file, the keywords MACHINE and UNIT are now read correctly along with the REMOVE keyword for actions that open a generator.

General: Fixed a bug that would cause a case to freeze when attempting to set the Difference Flows Base Case. This could occur in cases with only a few branches defined as Breakers.

April 28, 2015

Features and Improvements

Contingency Analysis Tool: Added new field with branches, "Contingency ResultsMax % Ld Loading Direction", that shows the direction of flow for the branch at the maximum loading level under all contingencies for which this branch is a violation.

Sensitivity Calculations: For TLR calculations, determine the island in which the calculations occur based on the island of the TLR element. If the element's terminals are in different islands, no calculation is done. When doing the calculations, only the buses in the transactor object that are in the same island as the TLR element will be used. Previously, we would not do the calculation and notify the user that the transactor spanned multiple islands. When doing the weighted calculations for areas and injection groups, we also only include the buses that are in the same island as the TLR element.

Transient Stability: Added reading of the AMETA record from a DYD file to indicate storage of angle information to transient stability results.

Bug Fixes

Contingency Analysis: Fixed bug with linear DC contingency analysis if a contingency causes the system slack to be islanded. The results would show very high flows and overloads on branches that are in the island when they should really be zero.

File Formats: Fixed a bug reading the UCTE files where blank lines in the description comments at the beginning of the file caused an access violation.

General: When creating a new branch that connects to a dummy bus of an existing multi-section line, remove the multi-section line record. If attempting to create a multi-section line through an auxiliary file and at least one dummy bus connects to other buses than the terminals of the MSline or other dummy buses, do not allow the multi-section line to be created. Messages are written to the log indicating MSLines are being removed or not created.

April 20, 2015

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Cleaned up how the creation of a star bus is handled when creating a three-winding transformer from an AUX file. Previously you had to input a star bus that was an existing bus in the case, and thus had to bother create this bus ahead of time and know its number. Now the user may optionally enter special strings for BusIndentifier:3 as follows:

Number : enter an unused bus number and Simulator will create this bus as part of creating the three-winding transformer
STAR : enter this and Simulator will create a star bus by starting at the primary bus number and incrementing by 1 until a unique number is found
STARMAX : enter this and Simulator will create a star bus with a number equal to the maximum bus number plus 1
STAR98765 : enter this and Simulator will create a star bus by starting at the number given after STAR and incrementing by 1 until a unique number is found

Syntax Note: You may optionally put a spaces between "STAR MAX" or "STAR 98765”. If the string starts with STAR but doesn’t match this syntax we default to treating it as though it said STAR only.

PV and QV Curve (PVQV) Tool: With the QV Curve Tool added an option to allow specification of QV Make-Up Power. Previously, any MW changes during the QV curve tracing were made up at the system slack bus. Now can choose to use the system slack bus or the same option that is set as the Contingency Analysis Make-Up Power option.

Bug Fixes

Contingency Analysis: Fixed bug that prevented you from creating a Custom Monitor for Contingency objects using an auxiliary file.

Contingency Analysis: In the Contingency Violation List, change the column header to "CTG: Category" for the category list that originates from the contingency to distinguish between the Category of the limit violation.

Integrated Topology Processing (ITP): Fixed an access violation caused by creating branches through a Post-Contingency Auxiliary file while the case is consolidated. Objects are not allowed to be created from an auxiliary file while the case is consolidated.

Transient Stability: Added error message when a NAN value is encountered in the network solution to show the bus at which this occurs.

Bug Fixes

April 8, 2015

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed "Percent" variablename for BRANCH objects for the more concise file format to represent the "% of Limit Used". Previously it was representing the "% at To Bus". Added variables "PercentFrom" and "PercentTo" to the concise file format

Case Information Displays: Fixed bug for filtering BRANCH objects by the owner in the Area/Zone/Owner filters. The problem was that we were checking both the owner of the terminal buses and the owner assigned to the branch. If both bus owners did NOT meet the owner filter, even though the branch owner did meet the filter, the branch would not be displayed. This has been fixed. This effected the use of filtering on branches everywhere in Simulator including locations like Auto-Insert Contingency definitions which make use of filtering.

File Formats: Added writing out voltage high/low normal/emergency limits with RAW format >= version 33. Previously we were reading this input but were not properly writing it back out. to the RAW format.

March 31, 2015

Bug Fixes

General: Fixed an access violation caused by deleting objects that are in contingency violation records. We were only checking for the object to appear once as a violation, but the same object could appear as different violation types. This was causing an access violation when trying to save the case to PWB.

March 20, 2015

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added two optional parameters to the SendToExcel script command, [Header_List] and [Header_Value_List]. These allow user specified headers and values to be included with the object fields.

Transient Stability: Added a new REEC_C model that permits modeling of a battery storage device allowing a negative Ipmin (to represent charging) and providing a charging state which can result in a modification of the limits of the Ip.

Auxiliary Files (SCRIPT and DATA Sections): The SaveYBusInMatlabFormat script command has a parameter to indicate if voltages should be included or not in the file. This wasn't being applied so the voltages were always saved. This has been fixed.

GIC: Fixed bug in which transformer configuration changes made on the GIC Transformer case information display were not getting updated on the GIC Transformer dialog that can be accessed from the Branch dialog.

Transient Stability: After a severe event, do not perform optimization on the network solutions until a fixed number of time steps have passed.

Transient Stability: Made changes to the LHFRT and LHVRT machine models to include the alarm parameter.

March 16, 2015

Features and Improvements

Contingency Analysis Tool: Added support with LHVRT transient stability model to trip generators in the power flow (steady state) contingency analysis if the voltage thresholds of the LHVRT are met during the contingency process.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed error with ":ALL" qualifier returning the number of fields for the Bus object BusMCMvarValue field. Also fixed and access violation associated with returning these values.

Case Information Displays: The field (Contingency ResultsMaximum Loading) that reports the highest loading of a branch over all contingencies should be reported as a percentage. This has been fixed.

File Formats: The number of Limit Groups that can be stored to a PWB file is limited to 127 in Simulator version 18. Reloading a PWB that was saved when more than 127 Limit Groups existed would result in objects being assigned to seemingly random Limit Groups. To correct this, any Limit Group beyond 127 will not be saved to the PWB and objects using these Limit Groups will be assigned to the Default Limit Group. Messages will be written to the log indicating which Limit Groups are not being saved to the PWB. Simulator version 19 will correct this problem completely and any number of Limit Groups can be saved.

GIC: Fixed GIC bugs associated with pasting in electric field time points.

PV and QV Curve (PVQV) Tool: Modified so that the name of the contingency is not included in the plot legend captions when creating a plot that only shows information for one contingency.

Transient Stability: Modified so that the name of the contingency is not included in the plot legend captions when creating a plot that only shows information for one contingency.

Transient Stability: Modified TLIN1 model so that multiple TLIN1 can be assigned to the same end of a branch. The Device ID must then be unique.

Transient Stability: Modified how reading line relays assigned to sections of multi-section lines is done. Previously for any line relays for which the end of the branch to which the relay is assigned matters, Simulator would always assign the relay to either the first or last section of the multi-section line and the section number in the DYD file was ignored. This has been changed so that the section number is now read and the relay can be assigned to any section of the multi-section line. Note: this probably is not good practice in general as the tripping any section of a multi-section line will trip all of them so having a separate relay for every section is unnecessary.

March 6, 2015

Features and Improvements

Case Information Displays: Added a new field for branch objects to the "MWSurge Impedance Loading". This will show the surge impedance loading on the line.

File Formats: When reading the hdbexport CSV file, fixed SVS parsing code so that AVR status is used properly.

PV and QV Curve (PVQV) Tool: Added a new button with PV plots to save plot images to file.

Transient Stability: Added support for the LSDT3 load relay models

Transient Stability: Added support for the LSDT7 load relay models

Transient Stability: Added support for GP2 relay model.

Transient Stability: Modified reading of the DYD file so that when the IFMON record is encountered we modify all our options regarding storing results to include the MW and Mvar flows on interfaces.

Transient Stability: Added a check at the end of reading a DYD file to determine if there are loads which do not have any static/algebraic stability models assigned to them. If this is the case, then a dialog would previously appear asking the user to choose a default load model. This dialog caused more confusion than clarity, thus it has been modified so that instead messages are written to the log notifying the user that all loads that do not have static load models will default to a "Constant Current P, Impedance Q". Also checking is done to see if there are ALWSCC models assigned to some areas but not others, and if this is the case then log messages are written to notify the user that some areas do not have ALWSCC models and list those areas.

Bug Fixes

PV and QV Curve (PVQV) Tool: Made fix so option to only save plots of critical scenarios is included when saving the aux file with all PV settings including plots.

Transient Stability: Modified treatment of Exciter Saturation which involve the calculation "VFE = Ve*Sat(Ve)". The trouble was with the Scaled Quadratic function: Sat(Ve) = [B*(Ve-A)^2]/Ve. In highly anomolous situations in which Ve --> 0, Simulator's calculation of Sat(Ve) was resulting in a floating point error due to a divide-by-zero. This has been fixed by instead simply evaluating the entire function "Ve*Sat(Ve) = B*(Ve-A)^2]".

Transient Stability: When reading in a branch relay (such as LOCTI, TIOCRS, TLIN1) from a DYD file, if the branch is not found then Simulator will also look to see if the terminal buses specified are the terminal of a three-winding transformer with the appropriate circuit id. If they are, then we will assume that the model is assigned to the winding of the three-winding transformer specified as the first bus in the DYD file.

Transient Stability: When reading CCOMP model from a DYD file, only the first 2 parameters are now required. Additional parameters if omitted are assumed to be zero.

Transient Stability: Fixed reading the last 2 parameters of the WNDTGE from a DYD file

Transient Stability: The user could configure options to storage of Injection Group results to hard-drive, but this was not actually being done when chosen. This has been fixed.

March 4, 2015

Features and Improvements

PV and QV Curve (PVQV) Tool: Added option with PV plotting to specify how the objects on the plots are identified, i.e. number, name_kv, or label.

Bug Fixes

File Formats: Added error checking when loading in a UCTE file to detect parallel branches that have the same circuit ID. This is not allowed in PowerWorld Simulator, but we were still adding the second branch resulting in inconsistency in Simulator. This is now handled by processing the list of branches after loading the UCTE file and automatically assigning a unique circuit ID if duplicates are found.

Integrated Topology Processing (ITP): When using the option to save a consolidated case and convert shunts to blocks, an incorrect nominal Mvar value could result for the consolidated shunt if composed of original fixed shunts that contained no blocks. This has been fixed. Now also correctly sum up the total Nominal G.

Optimal Power Flow (OPF): When trying to obtain bus information on the MW price details in the OPF solution using script commands and access the filed BusMCMWValue:1, BusMCMWValue:2 and so on, the values were not being returned properly. These values were only being calculated when the OPF dialog was opened to the tab which shows these values. It has been fixed so that these values are always calculated now so that they can be obtained when using scripts or SimAuto.

Transient Stability: modified throughout to handle FEX() exciter rectifier function when the Ve values falls toward zero. Previously for some models (REXS, REXSYS, REXSY1, EXAC1A, EXAC1, EMAC1T, and ESAC5A) this could cause a problem when Ve went to zero because the input the FEX function would go to +/- infinity.

March 3, 2015

Features and Improvements

PV and QV Curve (PVQV) Tool: Added new option with PV plots to only save a specified number of critical scenario plots to file. This is done on a plot-by-plot basis. When plotting critical scenarios, the options with contingencies that determine if scenarios should be plotted are ignored.

Bug Fixes

Fault Analysis: Modified reading sequence values for transformers from an SEQ file so that there is a check on the value existing in the record being read before trying to read it, otherwise it will default the value to 0. This applies to all of the sequence impedance values read for each record.

File Formats: Fixed error in loading in Generators from the UCTE file format

File Formats: Fixed error when loading a RAW file if the first entry in a line of text was a comma indicating that the first parameter of that line of text was supposed to be the default value

February 27, 2015

Features and Improvements

File Formats: Added ability when loading the KML file for ERCOT to have it create parallel transmission lines between the same 2 buses if there are duplicate entries in the KML file.

Transient Stability: Added support for PV1G machine model and the PV1E electrical model.

Transient Stability: Added option with LOCTI Relay to trip the entire three-winding transformer or only the monitored winding.

Transient Stability: Added more parameters to WNDTGE governor model.

Bug Fixes

Available Transfer Capability (ATC) Tool: Update the actual MVA limit stored with transfer limiters as individual limiters are iterated on. The limit could change from the original value due to contingency actions that change line ratings.

File Formats: When loading in a RAW file, estimate voltages at dummy buses of multi-section lines. Even though the buses are explicitly in the file the voltages might not be good depending on the process that created the RAW file.

File Formats: When loading in a RAW file, estimate the voltages at three-winding transformer star buses if the voltage is given as 1 pu and 0 deg. angle. This most likely indicates just a default value and could cause solution problems.

PV and QV Curve (PVQV) Tool: Fixed a bug with PV analysis that would not calculate dV/dQ sensitivities correctly under certain circumstances if a contingency did not actually implement any actions.

February 23, 2015

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added optional parameter, SetOutOfServiceBuses, to the CalculateTLR script command. If set to YES, this will set the sensitivities of out of service buses to the sensitivity of the closest in-service buses. Default value is NO.

Auxiliary Files (SCRIPT and DATA Sections): Added CTGApply("ContingencyName") script command to apply the actions in a contingency without solving the power flow.

Auxiliary Files (SCRIPT and DATA Sections): Added two new script commands, StoreState and RestoreState, that will allow user to store and restore a system state while in Run Mode.

PV and QV Curve (PVQV) Tool: Added options to allow saving PV plots to file at the end of a PV run.

Sensitivity Calculations: Added option when doing TLR calculations for injection groups that will allow offline devices to be included in the calculation.

Bug Fixes

Transient Stability: Modified column headings for options to specify what to save to RAM and column headings showing the actual transient results in case info displays. This was done to ensure column headings were unique so that copy/paste from Excel still functioned properly.

February 16, 2015

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): OpenWithBreakers and CloseWithBreakers script commands now allow the specification of any branch device type that can be switched in the SwitchingDeviceTypes parameter.

Auxiliary Files (SCRIPT and DATA Sections): The SendToExcel script command now allows an optional parameter SortFieldList to specify the order in which the fields should be sent to Excel. The script command parameters are now SendToExcel(objecttype,[fieldlist],filter,UseColumnHeaders,"workbookname","worksheetname",[SortFieldList]).

File Formats: Added the Simulator software version number and build date to a comment at the top of an exported PTI RAW file.

General: The number of limits that can be defined with branches has been increased to 15.

Bug Fixes

Contingency Analysis: The Text File Report Writing option could produce an error. This has been fixed.

Contingency Analysis: Fixed a bug when using the iterated linear CTG method and the Amount of a line rating change is specified using a model expression or field. These values were not being used correctly during the iterations.

Contingency Analysis: Fixed a bug when changing the rating of a line with one of the DC methods and setting the Limit Set line percentage to something other than 100%.

Sensitivity Calculations: The TLR sensitivities on interfaces containing phase shifters while using the Lossless DC with Phase Shifters option might not calculate the correct results. This has been fixed.

Sensitivity Calculations: When using DC method for TLR calculations, DC options for ignoring r or g, ignoring transformer impedance correction tables, and ignoring phase shift angle effects were not properly being included when doing a calculation on a line. This has been fixed.

Transient Stability: During a transient stability run hitting the Pause button and changing the simulation End Time could result in the simulation staying paused even after it was started again. This has been fixed.

Transient Stability: In Transient stability models REEC_A and REEC_B, fixed bugs when pasting from Excel into a case information display.

Transient Stability: Modified the transient contingency event so when you choose to "Set or change PRef", the following precedence is now followed (1) Use Plant Control model that accepts a Pref signal such as REPC_A, (2) Use a Pref controller such as WTGTRQ_A, (3) Use an exciter such as REEC_A, (4) use the Governor model. Previously the exciter was missing so REEC_A could not have it's Pref changed by a contingency action.

General: Fixed access violation that occurred when clicking on a condition on the filter logic visualization diagrams.

Oneline Diagrams: Fixed access violation that could result when attempting to add a new multi-section line to a oneline and then hitting Cancel on the Multi-Section Line Information dialog to not actually insert the new multi-section line.

PV and QV Curve (PVQV) Tool: Fixed the list of available fields for better reporting of the PV and QV results when using Track Limits.

Transient Stability: Added an event in the Events table to indicate that the network solution failed during the simulation.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): When loading in a display auxiliary file (*.AXD), identifying objects by label, and empty labels exist, an access violation could occur. This has been fixed.

Contingency Analysis: The contingency SETTO actions might not set the output to the specified value if multiple actions were applied to the same device. This has been fixed.

Integrated Topology Processing (ITP): Subnets were being defined based on the user specifiable field of Allow Consolidation for a branch. Subnets should only be based on whether a device is a switching device or not. This has been fixed.

Integrated Topology Processing (ITP): The process that would merge superbuses together if they were connected by a radial open breaker was causing open breakers to be lost during the consolidation process if the open breakers were marked to not be consolidated by setting the Allow Consolidation field to NO. This has been fixed.

Transient Stability: Reset the Solution Time Total for a contingency at the beginning of a run.

January 21, 2015

Features and Improvements

Contingency Analysis Tool: Injection Group contingency actions using Merit Order or Merit Order Open now include loads in addition to generators. If using Merit Order Open and both gens and loads exist in the injection group, only loads will be opened if the change is to increase injection and only generators will be opened if the change is to decrease injection. When using Merit Order, both gens and loads will move to their appropriate limits. Loads where both the Min and Max limit are 0 can only move to 0 MW. If using Merit Order Open and the change is to increase injection and no loads exist in the injection group, generators will be moved toward their max limits instead. If the change is to decrease injection and no generators exist, loads will be moved toward their max limits instead.
*** You may need to modify your injection groups if you have been using Merit Order with injection groups containing both loads and generators and you want to maintain the same functionality. ***

General: If using the Scale tool to scale an Injection Group and using Merit Order Dispatch, loads will now be included in the dispatch. Previously, any loads in the injection group were ignored. Loads will move towards either their minimum or maximum MW limit as appropriate. If both the minimum and maximum limits are 0, loads will only be allowed to decrease to 0 MW. Mvar load will be adjusted by keeping a constant power factor.
*** You may need to modify your injection groups if you have been using Merit Order with injection groups containing both loads and generators and you want to maintain the same functionality. ***

PV and QV Curve (PVQV) Tool: When using Injection Group Ramping option for Merit Order Dispatch, loads will now be included in the dispatch. Previously, any loads in the injection group were ignored. Loads will move towards either their minimum or maximum MW limit as appropriate. If both the minimum and maximum limits are 0, loads will only be allowed to decrease to 0 MW. Mvar load will be adjusted by keeping a constant power factor.
*** You may need to modify your injection groups if you have been using Merit Order with injection groups containing both loads and generators and you want to maintain the same functionality. ***

Time Step Simulation: When changing the injection of an Injection Group and using Merit Order Dispatch, loads will now be included in the dispatch. Previously, any loads in the injection group were ignored. Loads will move towards either their minimum or maximum MW limit as appropriate. If both the minimum and maximum limits are 0, loads will only be allowed to decrease to 0 MW. Mvar load will be adjusted by keeping a constant power factor.

Bug Fixes

Transient Stability: Fixed a bug in Distributed TS. When an error occurred with COM, it was obscured by a secondary access violation; this is now resolved.

Bug Fixes

Sensitivity Calculations: Fixed errors with the Multiple Meter, Multiple Control Change calculations when calculating using Integrated Topology Processing. Removed limitation that would only allow up to 500 controls to be selected.

Transient Stability: Fixed potential error in a wind turbine model when a fault is applied at its terminal. Under rare circumstances, this error prevented the wind turbine's real power from recovering after a fault.

January 7, 2015

Bug Fixes

Available Transfer Capability (ATC) Tool: Fixed an access violation that could result when running ATC analysis with contingencies containing multi-section lines that have shunt devices at dummy buses.

Contingency Analysis Tool: Added option to create stuck breaker contingencies. This will process each contingency that has explicit breaker outages defined and create new contingencies by treating each breaker as stuck in turn. The new contingencies will be comprised of all existing elements, minus the stuck breaker outage, plus open actions for breakers that are identified to isolate the stuck breakers.

Contingency Analysis Tool: Added option to create expanded breaker contingencies. This will convert any "Open with Breakers" or "Close with Breakers" contingeny actions into Open actions on explicit breakers. This will permanently modify the contingency definitions.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): When updating a ContingencyElement using a DATA section instead of a SUBDATA section, all of the parameters that are specified as part of the action but not used uniquely to identify an element were not being updated. This has been fixed.

Fault Analysis: Modified the calculation of the internal voltage for a generator.

File Formats: When writing out sequence data to the PTI file format for versions 33 and greater, now write ouf end of section kesy for zero sequence fixed shunt data and zero sequence machine data.

GIC: Fixed bug with display of transformer GIC Model Type parameter.

Transient Stability: The option to show the logo in the Title Block of a plot was being read in the opposite of how it was saved in a PWB file. This has been fixed.

Transient Stability: The Tripped Gen and Tripped Load values shown with contingency summary information could not be loaded from AUX files. This meant that this information was not available when using Distributed Computing for transient analysis. This has been fixed.

December 22, 2014

Bug Fixes

File Formats: When loading a RAW file if a bus is marked as a slack bus, but does not have any generators connected to it, Simulator will now automatically remove the slack bus designation and write a warning to the message log.

Transient Stability: Prevent access violation when saving to hard drive and the full drive is not specified in the name of the path.

User Interface Dialogs: Made some changes to the multi-section line dialog to update properly if the multi-section line being displayed somehow changes while the dialog is open. This could happen if a terminal of one of the branches within the multi-section line is moved.

User Interface Dialogs: When right-clicking on a list of generators, shunts, or transformers and choosing to save to an EPC file snippet, a dialog appears asking if you would also like to save the bus records for the regulated bus in addition (to ensure you're saving any changes in regulated bus voltage correctly.) Unfortunately this prompt would appear for every object selected, so if you selected 600 generators to save the dialog would appear 600 times. There is now the ability to choose "Yes to All" and "No to All".

December 17, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Adding command line parameters to write out the machine ID and also to load a license. Allows for scripting.

Case Information Displays: Also added the ability to use filtering across other object types for the InterfaceElements. They can now use Branch, Gen, Load, Interface, Injection Group, and MSLine filters directly.

Power Flow Solution: When reading in an EPC or RAW file which contained multiple slack bus designation for one electrical island, Simulator picks on of these as the slack and removes the other. An appropriate message is then written to the message log alerting the user of this. This message was then being repeated every time a power flow solution was done. The ongoing annoying messages were removed and only the first message will be shown now.

Transient Stability: Added ability on Transient Stability Plot titles and axis titles to use the special string "@CTGMemo" to include the memo of the transient contingency in the plot

Bug Fixes

Case Information Displays: Fixed the "Selected?" field of an interface element. It was getting the results from the object to which the interface referred. For example, an interface element which was for a Branch would return the branch's selected field. It should return the Selected field of the interface element itself.

Integrated Topology Processing (ITP): A bug was introduced when adding the improvements to consolidation on November 17, 2014 to more completely consolidate unnecessary open switches. This has been fixed.

December 15, 2014

Features and Improvements

Model Explorer: Show the "Branches By Type" folder in the Model Explorer regardless of whether the Integrated Topology Processing add-on has been purchased.

Transient Stability: When choosing a generator as the Angle Reference in the Result Options which is presently out-of-service and choosing to use an angle reference which uses that generator, Simulator will now create a validation warning alerting you of this problem. The simulation will still run, but the angle reference will be the synchronous reference frame (no shift) instead of your choice.

Transient Stability: When choosing a generator as the Angle Reference in the Result Options which is not a synchronous machine and choosing to use this generator internal angle, Simulator will now create a validation warning alerting you of this problem. The simulation will still run, but the angle reference will be the synchronous reference frame (no shift) instead of your choice.

Bug Fixes

Available Transfer Capability (ATC) Tool: ATC option to enforce generator MW limits with linear step is now used when using the iterated methods instead of just automatically enforcing the limits if all other options are set to enforce limits. This will allow users the option to use the same functionality that was used in version 17. This option is not applicable if using the Economic Merit Order option with injection group ramping. In this case limits will always be enforced if other options are set to enforce limits.

Contingency Analysis: When doing Quick Insert of Single Element add the new element to the end of the list of contingencies. Trying to add to the selected location doesn't make sense if there is any sorting applied to the list and this could royally screw up the linking of the contingencies. This will prevent a situation in which existing contingencies appear to disappear when doing a Quick Insert.

GIC: Fixed access violation that could occur when using the GIC scalar regions

December 8, 2014

Features and Improvements

General: Added button to open Monitors dialog so that they can a now be defined in Simulator. Monitors are used with the Trainer tool and allow for the triggering of alarms when specified events occur.

Retriever: Moved settings for alarm fading from the data model to the real time global options, and added fields (sgAlarmBackgroundFading, sgAlarmFadeColor) to store them.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): The Title Block Height and Right Memo Width for a plots created from the Plot Designer could not be set from an auxiliary file. This has been fixed. This affected the Transient Stability and PV tool plots.

Oneline Diagrams: Fixed bug in which when a saved contour was initially displayed its saved brightness and reverse colors were not being used.

Oneline Diagrams: Changed the default setting to false for the contouring option to use the GPU to accelerate the contour calculation.

Optimal Power Flow (OPF): Fixed potential access violation that would only occur in an OPF solution if all three of the following conditions were met for a generator that was configured to be on OPF control.
1. (MaxMW < MinMW)
2. abs(MaxMW-MinMW) < 0.02 MW
3. abs(PresentMW-MinMW) < 0.02 MW

Transient Stability: Changed the ordering of the MOTORX parameters to match the ordering of parameters in the CMPLDW model. We had fixed the CMPLDW a year or more ago to have the following order: Vtr1, Ttr1, Ftr1, Vrc1, Trc1, Vtr2, Ttr2, Ftr2, Vrc2, Trc2. This had not been fixed in MOTORX. As a result when using the feature to expand the Composite Load Model into the power flow case we were not properly populating the MOTORX models.

Transient Stability: Fixed bug on loading the SIMPLEOC model.

Transient Stability: Fixed bug in Induction Motor TotalQ reporting. This only affected the reporting and did not affect the simulation.

Transient Stability: Fixed access violation when you delete all of the contingencies showing in the multiple contingency table.

Transient Stability: Fixed access violation that could occur when closing a case containing a FACRISC model.

Transient Stability: Fixed error in autocorrect of the R parameter of the GPWSCC model.

Transient Stability: Fixed numerical precision in message log text indicating the load bus voltage at the end of a distribution equivalent is too low. Values such as 0.9477 were appearing as 0.95.

November 21, 2014

Features and Improvements

Case Information Displays: When using the Find Text in Oneline tool, the case information table listing all of the display objects found with the specified text now has the Layer Name available for the objects.

Contingency Analysis Tool: Time Delays can now be specified with power flow contingency actions. This serves as a relative ordering for the implementation of actions. Actions with the smallest time delay will be applied first during the TOPOLOGYCHECK and POSTCHECK solution steps.

Sensitivity Calculations: Provide access to the Loss Increase % value found on the PTDF dialog through the PWCaseInformation objecttype and LinePTDFLosses variablename.

Bug Fixes

Case Information Displays: An access violation could occur or the status change might not register when using the Toggle feature to change the status of Line Shunts in Line Shunt case information displays. This has been fixed.

Integrated Topology Processing (ITP): Fixed a consolidation error that could result in a dead bus being picked as the primary node if it is a regulated bus. This could result in a failed power flow solution.

November 17, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): When choosing to save settings to an auxiliary file from the Contingency Analysis Dialog, we now automatically append ", AUXDEF, YES" to the DATA section headers of the following objects so that those objects are always created when loading the auxiliary file and a dialog does not appear prompting the user about this: LimitSet, ModelExpression, ModelCondition, ModelFilter, CustomMonitor, various Contingency Definition objects

Auxiliary Files (SCRIPT and DATA Sections): When choosing to save settings to an auxiliary file from the Transient Stability Dialog, we now automatically append ", AUXDEF, YES" to the DATA section headers of the following objects so that those objects are always created when loading the auxiliary file and a dialog does not appear prompting the user about this: TSLimitMonitor, TSContingency, TSContingencyElement, TSPlotSeries, TSPlotVertAxisGroup, TSSubPlot, TSPlot

Auxiliary Files (SCRIPT and DATA Sections): When choosing to save the PV Curve Plot definitions to an auxiliary file from the PV Curve Dialog, we now automatically append ", AUXDEF, YES" to the DATA section headers of the following objects so that those objects are always created when loading the auxiliary file and a dialog does not appear prompting the user about this: PVPlotSeries, PVPlotVertAxisGroup, PVSubPlot, PVPlot

Auxiliary Files (SCRIPT and DATA Sections): When choosing to save Limit Monitoring setting to an Auxiliary File from the Limit Monitoring Dialog, we now automatically append ", AUXDEF, YES" to the DATA section header of the LIMITSET object so that those objects are always created when loading the auxiliary file and a dialog does not appear prompting the user about this.

Auxiliary Files (SCRIPT and DATA Sections): When choosing to save settings to an auxiliary file from the Available Transfer Capability Dialog, we now automatically append ", AUXDEF, YES" to the DATA section headers of the following objects so that those objects are always created when loading the auxiliary file and a dialog does not appear prompting the user about this: TransferLimiter, ATCLineChange, ATCLineChangeB, ATCGeneratorChange, ATCZoneChange, TATCInterfaceChange, ATCScenario

Auxiliary Files (SCRIPT and DATA Sections): When choosing to save settings to an auxiliary file from the Default Drawing Values for New Objects Dialog, we now automatically append ", AUXDEF, YES" to the DATA section headers of all the option objects so that those objects are always created when loading the auxiliary file and a dialog does not appear prompting the user about this.

Auxiliary Files (SCRIPT and DATA Sections): Added Left, Top, Width, and Height parameters to OpenOneline script command to specify form position when opening one line diagram. Syntax of script is now OpenOneline("filename", "view", FullScreen, ShowFull, LinkMethod, Left, Top, Width, Height).

File Formats: Added a new pop-up message to question the user it they want to save the bus records when saving an individual shunt, gen or transformer to an EPC file.

Integrated Topology Processing (ITP): Modified consolidation of superbuses to iteratively remove superbuses that contain ONLY switching devices that are connected to other superbus only by open switching devices. These are of no significance so merging into a superbus removes the clutter.

Integrated Topology Processing (ITP): Modified consolidation so that if a switching device that is directly in parallel (between exact same buses) with a non-switching device then the switching device is internally flagged to prevent consolidation due to this switch. This is done to prevent series capacitors from being removed from the model when they are bypassed by their bypass circuit breaker. Note that the series cap can still be completely consolidated if the more complex network typically involving a disconnect causes their terminals to be at the same super bus, but prevent the obvious parallel switch is helpful.

Transient Stability: Min/Max, Events, and Summary information are now saved to a PWB file if not storing the Time Values to PWB.

Transient Stability: Added cross-current compensation model CCOMP which is an equivalent model to the COMPCC but with slightly different algebraic expressions. CCOMP specifies a Zc and Zt value instead of Z1 and Z2. The can be converted as follows however.

User Interface Dialogs: Added a Populate button on the LODF Screening dialog to populate Branch custom fields from the summary results after the analysis is complete. This is useful if you forget to set the options ahead of time or want to change the key fields used to identify branches in the summary.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed a bug in FixFlowArrowLineEnds script command. It was flipping the pointers, but not the bus numbers so the changes were not being stored to file.

File Formats: Fixed checking for -1 as an alternative ending character for an OTG file.

Optimal Power Flow (OPF): Prevent an infinite loop in the OPF calculation if trying to enforce phase shifter MW regulation limits in the OPF.

Simulator Automation Server (SimAuto): Return an error message when using the OpenCaseType function with an ArevaHDB export file and the file load fails due to an unexpected error in the file.

Transient Stability: Prevent storing transient limit monitor violations twice to a PWB file. If older files are read where there is the possibility of multiples of the same violation being stored, check for and remove any duplicates.

Transient Stability: When choosing to save settings to an auxiliary file from the Transient Stablity Dialog, we were not saving the Transient Limit Monitor objects. This has been fixed so they are now saved.

Transient Stability: Fixed error in keeping track of the transient contingency results for "Total Gen MW Tripped". Value was being calculated by multiplying the generator per unit power by the SYSTEM MVABase instead of the machine MVA Base.

Transient Stability: Fixed potential error when using a negative END time in a transient stability simulation.

Transient Stability: The Transient Stability Dialog was preventing a start or end time which was negative. You could specify a negative time in the case information display showing multiple contingencies, but the edit box for Start and End Time on the dialog was always limiting those values to between 0 and 9999. This has been fixed so negative times may be entered.

November 10, 2014

Features and Improvements

File Formats: When saving selected generator records to an EPC file, bus records will also be saved so that the generator setpoint information is available.

Integrated Topology Processing (ITP): When saving a Consolidated Case or when viewing the Consolidated Superbus in the Bus View, generally open switching devices are maintained in the model to show where they are. We have modified it so that if a CLOSED switching device is parallel with a open switching device we do not display the open switching device. CLOSED switching devices in this situation are unusual as they must be specified as Consolidate=NO or part of an interface or tie-line, so this is a special situation.

Integrated Topology Processing (ITP): Modified so that we consolidate a dead bus to its neighbors if all three of the following conditions are met:
1. It has no gens, loads, or shunts
2. It is connected to the rest of the system only by open AC branches
3. It is only connected to ONE other SuperBus through these AC branches
The objective here is to consolidate a disconnect and dead auxiliary bus.

Sensitivity Calculations: On the LODF Screening dialog added the ability to store the summary results to custom fields with Branch records.

Bug Fixes

General: Fixed access violation that could occur if deleting an island slack bus that was selected by Simulator.

Power Flow Solution: We will no longer turn control off for a transformer or switched shunt that is regulating the same bus as either a generator or an SVC that are on line drop control and there are voltage regulation setpoint conflicts. In this case it is up to the user to rectify any potential control conflicts. Enhanced the error messages to give a better idea of where there could be voltage control conflicts.

Sensitivity Calculations: Corrected the LCDF values that are displayed when using the LODF Matrix and LODF Screening tools. The LCDF values had previously been showing values used internally in Simulator to calculate the impact of line closures rather than the actual LCDF values.

Transient Stability: For GGOV1 governor, a when Ka = 0 the governor doesn't make sense because in this situation the output of the governor will NEVER go up. Even as it swings down during a simulation it is then stuck at the lower value forever. Ka=0 is rarely entered in input data but when it is, the intent is clearly to disable the rate limiter, so the Ka term is now ignored if Ka<=0. Also modified GGOV1 to ignore the rate limiter if Ta=0.

Transient Stability: Fixed bug with Pelec not being on the Trate (turbine rating) base for governor models.

Transient Stability: Fixed an access violation that could occur when showing transient Events results for all contingencies.

Transient Stability: The start time for a single transient contingency can now be specified as less than 0. Negative start times were allowed in the case info display, but the dialog was limiting time to a minimum of 0.

October 31, 2014

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): When getting Injection Group Generator MW Max Decrease or MW Max Increase values via an auxiliary file, the Generator MW Min Total and MW Max Total values were returned instead. This has been fixed.

Contingency Analysis: When loading a contingency element involving a change_by or set_to action for a generator in percent from an auxiliary file, this would erroneously show up as an unlinked element. This has been fixed.

General: When renumbering Multi-section Line dummy buses, either through the special text file or through a SUBDATA section, the default will now be to keep the original bus name instead of renaming to the new bus number if no bus number is specified.

Transient Stability: Modified the case info displays for Transient Contingency Elements so that we show time out to 6 decimal places by default because Time in simulator is precise to exactly 1 microsecond.

Transient Stability: Modified the reading of Transient Contingency Elements so that the string being read in will determine the precision of the Time used to look for that same event. Time in Simulator is precise to exactly 1 microsecond. Thus if an event occurs at 1.083333 and someone pastes in or reads from an AUX file an event at 1.0833 seconds, then previously Simulator would flag that as a NEW event. Now, Simulator will look at this string and determine that it is only precise to 100 microseconds. Therefore when searching for an already existing contingency event we will use a precision of one half that (50 microseconds). As a result we will treat 1.083333 = 1.0833 because they are within 33 microseconds of one another.

Transient Stability: Modified the list of all transient contingency elements definitions so that you can advanced filter this display, you can paste data into the case info display, and you can delete elements.

Transient Stability: Fixed bug in storing the Other field for the TIOCRS line relay model of the Current stored in amps. It was always storing a value of zero.

October 30, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added the MergeMSLineSections(Filter); It does the same as the Merge Lines right click in Model Explorer.

Auxiliary Files (SCRIPT and DATA Sections): Added the ability to use the special string @ to the file name to the deletefile script and to any script that uses the function InterpretFileNameIsOpenDialog to interpret the filename.

File Formats: Added the ability to not generate the default labels when using custom labels in hdbexport.

File Formats: Modified reading of the RAW file format so that if comments are found for data records of the format /* [ my label, my second label ] */, then labels will automatically be created for the object. The string parsing removes all leading and trailing /, *, or space characters. Then if the remaining string starts with a [ and ends with a ], we assume that what is inside the bracket is a comma-delimited list of strings representing labels.

General: Speed increase in expression parsing.

Power Flow Solution: Added option with a VSC DC Line to specify whether the DC MW Setpoint is interpreted as the MW flow on the "AC side" or "DC Side" of the converter. If there are not any converter losses modeled then this does not matter. Modified reading VSC DC Lines from a RAW file so that the DC MW Setpoint is interpreted as the "AC side" MW. When writing out to the RAW format, if the option in Simulator is set to "DC Side", then the appropriate AC flow will be calculated and written out to the RAW file instead.

Transient Stability: Adding simplified line OC model.

Transient Stability: Made a slight modification so the SET Power command for transient contingencies will interpret an actual MW value and convert it to a delta MW value if necessary instead of treating everything like a delta MW value.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed a bug that when in the dialog you were renaming the IG it was adding a copy of the IG that was "Renamed".

Contingency Analysis: When adding the ability to include a substation outage in the contingency record in the Oct 2, 2014 patch, a bug was introduced on the Contingency Element Dialog which caused the dialog to malfunction for the special elements listed AFTER Substation. These include Abort, Solve Power Flow, and Contingency Blocks. Elements would still function properly when defined by loading from an AUX file or loading PWB files. The bug only effected the dialog box and made it impossible to define Abort, Solve Power Flow, or Contingency Block elements.

General: Fixed an ambiguity with the math parser regular expressions that caused a syntax ambiguity between "<>" and "]" while still retaining a token length of one. Also fixing the ambiguities between ">" and ">=" and "

Power Flow Solution: The power flow might fail to converge if an SVC is located at a disconnected bus. This has been fixed.

Transient Stability: Fixed two issues with reading of JSIS format for modal analysis tool. If a comma was at the end of the lines in the csv files, it wouldn't read those lines. Also in RawTimeRangeCount, local_LastTimeSec was getting checked but was never being set which was causing errors.

Transient Stability: Bug fix associated with local_HasAMachineModel being set incorrectly.

October 16, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added new ability when pasting a string into a field (or by using the SetData() script command). The string can start the character & and then be followed by the objecttype, key fields, and then a variablename. When using a string of this type Simulator will parse to find the object referred to and then evaluate the variable name for that object and convert the string to the result of this evaluation. This feature can also be used in the Extra Strings in the SaveDataWithExtra() script command. An example of such as string is

"&Gen '563' 'ab' GenMW:0:8:3"

This would instruct that the MW output of with 8 characters and 3 decimal points for the generator at bus 563 with an genid 'ab' be used.

Auxiliary Files (SCRIPT and DATA Sections): When using the special string &ModelExpression or &objecttype key key variable:loc:digits:decimals,, if no digits or decimals are specified then we use 7 decimal places. We will now also remove any trailing zeros if no decimals are specified.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): When using the script command OpenCase() and the file loaded was invalid, then after completing the script command the power system case will be empty. This was causing an access violation which has been fixed. In addition to fixing the bug, we also added additional error messages to help the user notice that the opening of the case failed.

Case Information Displays: Modified case information displays so that the background color outside of the region occupied by rows and columns would obey the color of the background of normal cells in the table. Previously these parts of the grid would appear as white regardless of the colors chosen for the displays.

File Formats: There as an error in writing out VSC DC Lines to the RAW file format. This has been fixed.

October 14, 2014

Features and Improvements

Sensitivity Calculations: Added sensitivity calculations for dAmp/dControl and dMVA/dControl for the Multiple Meters, Single Control Change calculations.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): When using the LoadCSV() script command, an access violation occurred if an object was found. This has been fixed.

Auxiliary Files (SCRIPT and DATA Sections): When using the LoadCSV() script command if the CreateIfNotFound was set to YES, Simulator was still prompting the user. This has been fixed.

Bus View and Substation View Onelines: Modified to prevent the user from auto-inserting display objects on the Bus View. This did not cause any harm previously but was confusing. Also modified to prevent formating display objects on the Bus View for the same reason.

Contingency Analysis: When keeping track of the contingency result that returns the amount of "Total Islanded Load MW", we sum up the amount of load MW at any bus whose bus status is Connected in the reference state and then disconnected in the contingency solution. There was a bug that even loads which had a Status of OPEN in the reference state were included in this summation. This has been fixed.

Optimal Power Flow (OPF): Fixed a bug with numerical tolerances that are too small in the area constraint of an OPF solution.

Sensitivity Calculations: Fixed some sign errors with the Multiple Meters, Single Control Change calculations when calculating while in DC Power Flow Mode.

Transient Stability: There was a problem with OOSLEN line relay that was causing an access violation when the relay do not have any data. This has been fixed.

October 10, 2014

Features and Improvements

Contingency Analysis Tool: Added accounting of Total Dropped Load during a contingency. This shows the MW amount of load that was islanded due to a contingency action or opened due to a direct contingency action to the load.

Transient Stability: Added Level designation to Transient Events. Options have been added to easily display Events by specific Levels: Error, Info, Skipped, User, Transition, Model Trip, and Relay Trip. Result Event Reporting options have been added to specify if events are reported to the Message Log in addition to the Event table. These new options are especially useful when using the CMPLDW composite load model which has many possible events associated with it.

Bug Fixes

Available Transfer Capability (ATC) Tool: Before doing an iterated ATC method or using the ATC tool to increase the transfer AND the transfer is between areas/super areas AND the case AGC control is disabled, a check is done to see if the ACE values for areas and super areas that are on control is greater than its AGC tolerance. If the ACE values are too great an error will result and the study cannot continue. The user will have to reconcile the ACE problems in the case before the study can proceed.

File Formats: Bug fix for saving CROW import file settings to AUX.

Transient Stability: Fixed error in LHVRT and LHFRT models which could cause the generator to trip inappropriately.

User Interface Dialogs: Fixed bug in Model Condition dialog that would change the selected object after the Save As button was clicked. This could cause the wrong object to be saved with the Model Condition if the OK button on the dialog was then clicked.

October 8, 2014

Features and Improvements

Transient Stability: Added color to log text when loading in DYD files. "Missing" notes are written in gray. "Error" in red.

Bug Fixes

Available Transfer Capability (ATC) Tool: When using Distributed ATC, the ATC Extra Monitor results were incorrect. This has been fixed.

Case Information Displays: When using a piecewise linear cost function for a generator, Simulator continues to use the the "Cost Shift" and "Cost Multiplier" fields to determine the cost function. The case information display however would show these fields grayed-out indicating that these fields were not used. This graying-out error has been removed.

Optimal Power Flow (OPF): Fixed a tolerance issue that was causing an infinite loop in the OPF solution.

Transient Stability: Fixed an error in the SVSMO3 SVC model current calculations.

Transient Stability: Modified the result field names for voltage to be consistently: Volt (pu) or Bus Volt (pu).

Transient Stability: Fixed reporting of the "Total MW Load Tripped" during a transient stability contingency when using the CMPLDW model.

October 3, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added optional parameter to ReassignIDs; if "UseRight" is "YES", then the last two characters of the specified field will be used to create the new id rather than the first two characters. The parameter defaults to NO. The script command is now ReassignIDs(objecttype, field, filter, UseRight).

Contingency Analysis Tool: Added the ability to auto-insert a list of substation outages

File Formats: When using the case information display options from a table of switched shunts or transformers to save the records to the EPC format we now aalso save the bus records automatically as well. The EPC format embeds the voltage regulation information for the shunts and transformers in bus records. Saving the bus records additionally helps avoid some confusion, though the user still must be careful.

Transient Stability: Added error checking for WT3G2, WT3G, WT4G, WT4G1 and REGC_A so that if LVPL=0 then it ignores the low voltage power logic

Transient Stability: For LD1PAC, when fuvr=0 we were still reporting transient stability events related to the pickup of the under voltage relay even though it would never actually open anything. This has been fixed to no longer report these events if fuvr=0.

Transient Stability: Changed the CONV_IntMtnPP and CONV_Adelanto converter models to use a CosMinAngle equal to 0.95630476 instead of 0.956. It's a very minor change but using 0.956 signifies an minimum firing angle of 17.059 degrees which doesn't match the initial condition of 17.000 often seen in cases.

Bug Fixes

Transient Stability: fixed errors in using a CIM6 motor model which resulted in an access violation

Transient Stability: When reading a DYD file, netting records which had a line of text listing only ONE bus listed were not being properly read (2 or more worked fine). This has been fixed to properly read the buses and disable stability models.

Transient Stability: For generator transient stability models of SVCs, any MW output of the generator was not properly accounted for in transient stability. This has been fixed.

Transient Stability: Added a fix for the previous patch which ignored CMPLDW models which were negative.

October 2, 2014

Features and Improvements

Contingency Analysis Tool: Added a new contingency element for "Substation OPEN". This will open all AC Branches, DC Lines, and multi-terminal DC lines connected to the substation.

Contingency Analysis Tool: Added a new contingency element for "Substation OPEN with Breakers". This will open all breakers necessary to isolate all AC Branches and DC Lines which have exactly one terminal in this substation. Note: this will not open breakers necessary to isolate devices completely inside the substation, such as transformers.

Contingency Analysis Tool: Added a new contingency element for setting the resistance of a DC Line.

User Interface Dialogs: When using the Test button on the custom expression (or string expression) dialog, added additional error message when no object has been selected for one of the variables.

Bug Fixes

Power Flow Solution: Fixed an issue with the SVC solution. When the SVC was hitting MVARS or Reactive current limits it was oscillating a lot causing to iterate the voltage loop until the limit. Now it does not oscillate.

PV and QV Curve (PVQV) Tool: When saving PV results to a file, an unnecessary log file was also being written to hard-drive. This has been removed.

Transient Stability: Fixed error in handling transient stability DC line equations when the voltage controlling converter changed during a stability run because the original voltage controlling converter was unable to maintain the voltage schedule.

Transient Stability: Fixed error in the PDCI transient stability models that occurs for the south-north flow.

User Interface Dialogs: Previously after defining a piece-wise linear cost curve for a generator it was difficult to delete the points in the curves globally. Simulator would attempt to always maintain one MW/Price point in the curve to be "helpful" to the user. While this prevents the erroneous input information of specifying a CostModel of Linear without specifying points on the curve it was more annoying than helpful. The user interface has been modified to allow a user to delete all price points now and the OPF and Economic Dispatch algorithms have been modified to capture this situation and ignore generators specified as a Linear model but without a curve - treating this the same as a cost model of None. The easiest place to delete all points is in the Model Explorer under Optimal Power FlowBidsGenerator Bid Curves. Alternatively it can be done running the script command Delete(GenBid);

September 30, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added script command Remove3WXFormerContainer(filter) to delete 3 winding transformers matching the specified filter while leaving the internal 2 winding transformer structures intact. It takes one optional parameter, if you have a filter that specifies which 3-winding transformers you wish to delete.
Example usage -- to remove 3-winding transformers that meet the conditions specified by the advanced filter "Northern": Remove3WXFormerContainer("Northern");

Auxiliary Files (SCRIPT and DATA Sections): Added script command ReassignIDs(objecttype, field, filter) to automatically set the ids of specified Branches, Gens, Loads, or Shunts to the first two characters of a specified field. It takes each object of a specified type (currently "Branch", "Load", "Shunt", and "Gen" are supported), and sets that object's ID to the first two characters of a specified field. Again, an optional filter parameter allows you to use a filter to only run the command on a specific group of elements.

Example usage -- to reassign the circuit ids of all branches in the case to new ids specified in each branch's Custom String 3:
ReassignIDs("Branch", "CustomString:2");

Transient Stability: Added support for PTIST3 stabilizer

Bug Fixes

Transient Stability: Modified the Power-Speed curve on the WT3E and WT3E1 wind turbine so the power is in percentage of Rating Power. Previously we were using percentage of "Pmax".

Transient Stability: Fixed error in validation check when looking for small motors

Transient Stability: Fixed a bug with an LCFB1 model if the generator did not have a Governor model assigned to it. This was causing an access violation when storing the states and other fields.

Transient Stability: Fixed scaling problem in the power control for the WT3E, REEC_A, and REEC_B electrical controls. If the Rated Power (MWCap) of these models was not equal to the generator MVABase then there was a scaling problem

Transient Stability: Modified the WT3E1 electrical control to obtain the Rated Power from the WT3G1 or WT3G2 models by multiplying the parameters PRated*Number.

September 27, 2014

Features and Improvements

Transient Stability: Added error checking for using a distribution equivalent which could not support the load specified. This was caused because the distribution equivalent impedances are given on an MVABase that is proportional to the MW of the load. In a situation which had a load of 2.0 MW and 120 Mvar, the load would exceed the maximum power transfer of the distribution system because the Mvar values was so huge relative to the MW. An appropriate error message will now be shown.

Transient Stability: Modified to not model motors which are less than 0.01 MW and added appropriate warning message to indicate this

Transient Stability: added error checking for WT3E and WT3E1 model to disallow Kpp=0 AND Kip=0. That doesn't make any sense and is showing up in the MMWG cases at a generator.

Contingency Analysis Tool: Made parsing of name kV portions of OTG files more generic.

File Formats: When reading hdbexport CSV files, modified the prompt regarding unrecognized CBTyp entries. Dialog will appear but check-box on dialog will be available to specify if user choices should be saved to registry for use when loading future CSV files. This will be checked by default. In addition, an extra confirmation prompt appears if the user choices will result in a case with no Breakers.

Transient Stability: modified the validation check for GEWTG machine so that if the electrical model is EWTGFC or EXWTGE, but the fcflag does not match the expected value (0 for EXWTGE and 1 for EWTGFC), then the auto-correction routine will change the fcflag to match the expected value. The assumption is that the user specification of an electrical model is more reliable than setting of fcflag to 0 or 1.

User Interface Dialogs: modified the Set Selected Field Inside a Network Cut dialog so that the check box "Require paths to be energized" is checked by default.

Bug Fixes

Transient Stability: Fixed error when using the FACRI_SS switched shunt stability model if some of the shunts which the model refers to are set to None.

Transient Stability: fixed error in reporting of limit status and thus the reported state derivative of the pitch compensation for the WT3P model. Note it would still simulated correctly, it just wasn't reporting properly when it was at a limit.

Transient Stability: Fixed error in using the WPIDHY governor model that was introduced in September 23rd patch

September 23, 2014

Features and Improvements

Transient Stability: Added default parameters for model WEHGOV

Transient Stability: Added new stability model HYGOVRU which is really the same as HYGOVR

Transient Stability: Added an additional "Other Field" for induction motors to report the presently used Device MVABase used internally by Simulator. This can change throughout the simulation by load relays or by models such as CMPLDW.

Bug Fixes

Transient Stability: Fixed error when modeling a motor in CMPLDW which had been 100% tripped. Three-phase motors (either the A, B, C, or D) which are 100% tripped can not be restarted so Simulator will simply open these motors and stop integrating them.

September 19, 2014

Features and Improvements

Available Transfer Capability (ATC) Tool: Added new script command CTGCompareTwoListsofContingencyResults("Controllingfilename","Comparisonfilename"); A filename may be replaced with the word PRESENT to mean the presently open contingency list.

File Formats: Adding options to read limit options from hdbexport files. The fields below on the ITEM record indicate whether or not to treat the line limits as AMPS instead of MVA. The transformer option doesn't make much sense so a message will be printed to the log if it is ever true.
LNAMP=T
XFAMP=F
ZBRAMP=T
EQLNAMP=F

File Formats: modified to include option about whether to create 3-winding transformers when reading the hdbexport file.

File Formats: Also added AUX file support for setting the Delimiter used for creating labels when reading the hdbexport CSV file.

Power Flow Solution: Changed the way the 2-terminal DC line firing angle and tap control are handled when GammaMin = GammaMax. Under other situations once the maximum tap value is reached and the DC voltage is still above the desired setpoint, then Simulator will calculate a firing angle that exceeds GammaMax. This has been changed now so that if GammaMin=GammaMax, then the firing angle will remain constant and instead the DC voltage setpoint enforcement is abandoned and the DC voltage will be higher than the setpoint. When this occurs a prominently highlighted message will be written to the log. This change in control feature was added primarily to match the treatment in several ERAG/MMWG, PJM, and MISO cases we have seen recently which have some erroneous input data.

Sensitivity Calculations: Added new option to calculate sensitivities due to a change in generator MW injection for the Multiple Meters, Single Control Change and Multiple Meters, Multiple Control Change calculations.

Transient Stability: Modified reading of a GNET.idv file to allow multiple gnet sections in the same file to be read.

Transient Stability: added other field for CMPLDW to show the "Fraction not tripped on under voltage" for the Type 3 motors.

Bug Fixes

Contingency Analysis: Contingencies involving breaker actions will only use breakers. Load Break Disconnects will be included along with breakers when determining switched shunts to close and generators to close when using economic merit order dispatch. Script commands or GUI options to close or open with breakers will give users the choice to include load break disconnects along with breakers.

File Formats: When reading the hdbexport CSV files, modified reading of XF records so that if ID_XFMR values are not read at all then no three-winding transformers are created.

General: Modified the Equivalencing routine so that it does not consolidate before creating the equivalent.

GIC: Fixed bug in calculating whether a point is in a region; used with the GIC code.

Sensitivity Calculations: Fixed bug with calculations of LODF values in the LODF Screening tool when monitoring a different set of branches than the branches being outaged/closed.

Transient Stability: Fixed a bug that was causing an access violation when auto inserting and deleting previous contingencies

Transient Stability: Treatment for handling low voltages for GEWTG was missing and was added.

Transient Stability: fixed error in the PSS3B stabilizer. Using this stabilizer was causing an error when running a transient stability simulation

Transient Stability: A bug was occurring when opening a generator which had a COMP or other voltage compensator model assigned to it

Transient Stability: fixed error in displaying data for IVOEX exciter in the case information displays. The Max/Min values were shown as blanks.

Transient Stability: When one of the blocks on either an IVOEX or EXIVO exciter were configured such that A2=0, A4=0 or A6=0, then the block becomes a PI controller. The initialization of the PI controller was not done properly and has now been fixed.

Transient Stability: fixed initialization of the CompCC model so that the order in which models are initialized does not prevent matter. CompCC is assigned to a generator record but then refers to a second generator. Previously the generator with the CompCC model had to be initialized BEFORE the second generator. The software now handles the ordering.

Transient Stability: Fixed error with using a wind turbine model with an implicit step-up transformer. The voltage measurement was not working properly and is now fixed.

Transient Stability: modified EXAC1 and EXAC1A to include subinterval integration when Ta=0 AND Tb=0.

Transient Stability: modified ESAC5A to include subinterval integration when Ka/Ta is large.

Transient Stability: fixed error in the use of the WT2E power slip curve.

Transient Stability: Fixed error that only occurred when tripping a portion of Motor A, B, C, or D if it was a double-cage motor model inside of a CMPLDW or CMPLDWNF model. Error was an improper calculation of derivate of the rotor speed.

September 3, 2014

Bug Fixes

Case Information Displays: On the Bus Case Information Display, the "Bus Neighbor List (in service only)" field was reporting all neighbors regardless of branch status. This has been fixed.

Contingency Analysis: When calculating a multi-section line contingency using the linear methods, the results would not properly account for islanded generation or load if the dummy buses contained generation or load. This has been fixed.

Power Flow Solution: As part of Robust Solution Process, turn on SVC control if it was originally on.

Transient Stability: Modified so that in order for an electrical island to be considered viable it must have at least one machine model which is modeled as a voltage source behind an impedance (such as a synchronous machine). Therefore, islands which are created during a simulation by a switching action that result in an electrical island that contains only Type 3 and 4 wind turbines (and other machines modeled as a constant current injection) are not considered by themselves to be enough to support an island.

Features and Improvements

Bug Fixes

August 25, 2014

Bug Fixes

Transient Stability: Modified the reactive current injection for type 3 and type 4 wind-turbine models so that for voltages below 0.4 per unit, the current injection will linearly fall to zero at 0.25 per unit voltage

Transient Stability: Fixed bug in WT3E and WT3E1 models. The Ipmax limiter on the power command output was not being enforced.

August 21, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Allow string expressions to be referenced by name in addition to location number.

Case Information Displays: Added a new field for BRANCH, GEN, and SHUNT objects called "RegBus by ObjectID". When showing this field, the option that is used to specify which key field to use in SUBDATA sections is used to identify the regulated bus by either primary, secondary, or label identifiers. When reading from an AUX file any of these identifiers can be used to identify the regulated bus.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed access violation that could appear when using the CTGSolve script command to solve a contingency while the case is in DC power flow mode.

File Formats: When reading the ABB Spider format correctly read transformer values of regmaxv, regminv, and xftype when they are zero or blank.

General: Fixed an access violation that could result when using the MOVE command on a branch, the owner being used before the move is the default owner, and the from bus of the branch following the move is a different owner than the original default owner. Now if the branch has the default owner before the move we will force it to have the default owner after the move as well. The default owner is the owner of the from bus.

Transient Stability: Fixed error in reading the ZLIN1 model from a DYD file when nfar value is read as negative. This negative sign in the DYD file indicates the units of the r1ang1 and x1z1 values. Simulator encodes this distinction in the "Imp Type" flag instead. When nfar was read as negative value from DYD we were not properly setting the "Imp Type" flag.

August 19, 2014

Features and Improvements

Contingency Analysis Tool: Added options to open the Bus View or Substation View by right-clicking on a contingency violation.

GIC: Now have the ability to automatically incorporate scaling factors for geomagnetic latitude and earth resistivity according to the NERC Benchmark Geomagnetic Disturbance Event Description (Draft: April 21, 2014).

August 13, 2014

Features and Improvements

File Formats: When reading a RAW file, the options to specify the starting bus number of star buses are now stored in the computer registry.

Bug Fixes

PV and QV Curve (PVQV) Tool: The ability to access Devices at Limits for saving to a file with script commands was not working. Writing out this information has been fixed but the data cannot be read back into Simulator.

Transient Stability: The CLOD load model has extra parameters Vi, Ti, and Tb to specify a load level at which load should be dropped. This feature was not disabled by default but it is now disabled by default.

Transient Stability: Fixed a one time step delay in propogation of Eppr and Eppi when using a single cage motor model with the MOTORW (or inside the CMPLDW and CMPLDWNF models) model.

August 6, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Added "Simulation: Successful Power Flow Solution (but may have converged to a low-voltage solution)" and "Simulation: Power Flow did no Converge!" to the message log when running a power flow using script commands.

Auxiliary Files (SCRIPT and DATA Sections): Added new script command PVWriteInadequateVoltages("filename") that will write the inadequate voltages stored during a PV run to a comma separated file (CSV).

Fault Analysis: When defining multiple faults you now have the option to specify the position of the fault along the line. To save computation time, by default a location >= 50 assumes a fault at the To Bus and < 50 assumes a falut at the from bus. A checkbox has been added to instead add a dummy bus at the actual fault location.

Transient Stability: Added generator over frequency relay model called GENOF_PW. This allows monitoring of frequency at a specified bus or generator. When monitoring a generator only the generator will be opened when over frequency is detected. If monitoring a bus, generators, loads, and shunts connected at that bus will be opened when over frequency is detected. The relay can also be used for monitoring without actually tripping any devices.

Transient Stability: Modified the auto correction of the GENTPF and GENTPJ models for very low values of Xqpp. If (Xqpp = 0) or (Xqpp < 0.01*Xdpp), then we assume Xqpp is not known so we set Xqpp=Xdpp and thus remove all transient saliency. If Xqpp < 0.5*Xdpp then we set Xqpp=0.5*Xdpp. Xqpp and Xdpp should be very close to each other and values radically different cause numerical problems.

Transient Stability: Modify Vrmax or Vrmin of ESST1A exciter if necessary to initialize without limit violations.

Transient Stability: Fixed error with TSGetResults script command and TSGetContingencyResults SimAuto function. If results were requested for an open object, values for other objects would not show up in the results. Now only results for the open object will not be included.

Transient Stability: Fixed a bug with the PlayInRef model. At time 0 the value was not being changed from the initial value to the signal value specified at time 0.

July 23, 2014

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): The RenameFile script command will now allow special keywords (@DATETIME, @DATE, @TIME, @BUILDDATE, @VERSION, and @CASENAME) to be included in the new name of the file. The special keywords will be replaced with their actual value.

Integrated Topology Processing (ITP): When saving the consolidated case through the SaveConsolidatedCase script command, the contingencies were not being saved for the consolidated state. This has been fixed.

July 21, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): Modified new feature for script commands using the magic string "@CASENAME" so that the string is replaced with the present name of the case file. It now will NOT include the file extension of the case file.

Fault Analysis: added additional locations on the Fault Analysis Dialog to specify that current values be shown in per unit or Amps.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Fixed a bug when saving the Injection Group records using SUBDATA section and specifying to identify by label. It was saving using Name_NomKV instead. The reading worked fine, but the saving of the AUX file was incorrect.

Auxiliary Files (SCRIPT and DATA Sections): Fixed an error with reading the controllable fixed shunts for the switched shunt records in an AUX file.

Transient Stability: When reading a DYD file and encountering MOTORW or CPMLDW records with a negative MVABase specified, Simulator was seeing the negative value and setting it to 0.0 instead. This has been fixed to correctly read the negative value which has special treatment for those two data records.

Transient Stability: Added message log warnings when reading a DYD file with faulty CMPLDW records that had extra parameters. Previously no warning message would appear with the CMPLDW records as appeared with other types of records. In addition, previously the first extra parameter in the CMPLDW records would overwrite the MVABase of the record. It has been fixed so that extra parameters are ignored and an appropriate warning message is written to the log. Most frequently these extra parameters indicate an error in the data file.

User Interface Dialogs: Fixed a bug on the Limit Monitoring Settings Dialog when saving the settings to an AUX file. It was not properly saving the Area and Zone object "Report Limits" field (YES/NO field). This was only true on this dialog.

July 17, 2014

Bug Fixes

Power Flow Solution: Fixed a very rare error in phase shifter switching which could occur if impedance correction tables had very large values AND you were simultaneously enforcing discrete phase shifter steps. It was possible for the phase shifters to become stuck in this situation because of some internal hueristics to handle impedance corrections with large values. This has been fixed.

Transient Stability: Modified the MOTORW model for double-cage motor simulations. Previously, PowerWorld had assumed that MOTORW model dynamic equations were treated the same as MOTOR1, CIM5, CIM6, and CIMW but with the simplification that saturation was ignored and that Xl = 0.8*Xdpp. Customer testing showed that the they were actually slightly different dynamic models which give different results. We have modified the MOTORW to use these special dynamic equations instead.

User Interface Dialogs: On the system equivalencing dialog, when choosing to Delete the external system, it was possible for an access violation to occur if a 3-winding transformer had a terminal bus set to be equivalenced but the internal star bus was not set to be equivalenced. This has been fixed.

July 16, 2014

Features and Improvements

Auxiliary Files (SCRIPT and DATA Sections): modified so that the SaveData() and any other script commands that save something to a file now allow you to embed the NAME of the open case file to a file being saved using a script using the magic string "@CASENAME"

Oneline Diagrams: Added a new map projection that uses an Albers Conic Projection useful for Alaska.

Bug Fixes

Contingency Analysis: It was possible in the DC contingency analysis for an error to occur if the only generator in the entire case that could respond for MW make-up power was configured with MaxMW < MinMW. The error would cause Simulator to freeze. This has been fixed.

General: Fixed a problem when creating new buses with the area number specified to be 0. All buses need to be assigned to an area, and if none is specified, area number 1 should be the default. This wasn't happening correctly which would result in access violations when trying to view area information for a bus.

General: Fixed issue with executable resource generation that gave wrong build version in file properties within the Windows environment

Transient Stability: Made a fix so that load relay models that monitor the rate of change of frequency will calculate this correctly. The input into the derivative block was always set at the initialization frequency of 60 Hz. This affects models DLSH and LSDT8.

Transient Stability: Fixed some caption hint strings for the CMPLDW and CMPLDWNF models

Transient Stability: Fixed bug in the calculate of R2 for the MOTORW model if it represented a subtransient motor model. This could cause the the initialization of the motor to be slightly off.

Transient Stability: Modified MOTORW (and thus CMPLDW and CMPLDWNF) reporting so that values like torque and power are reporting in actual MW units instead of per unit. The per unit values for these can be difficult to interpret because the MVABase for these model is calculated in the model.

Transient Stability: Fixed an error with the SimAuto command TSGetContingencyResults. It wasn't working and was starting from zero no matter the input time was not zero.

Transient Stability: Modified the LD1PAC model (and thus CMPLDW and CMPLDWNF) so that during load initialization a breakpoint between operating on the stall curve (impedance) and the "2" curve (defined by Kp2 and Np2). This breakpoint will be set equal to the smaller of either Vstall or the intersection of the two curves for the power curve. During algebraic solutions the P and Q algebraic equations will flip between the stall curve and the "2" curve at this calculated breakpoint. Thus even if the motor stall timer (TStall) has not expired, the algebraic model may still move to the stall curve for voltage values below this calculated breakpoint.

June 27, 2014

Features and Improvements

Contingency Analysis Tool: New option with Injection Group actions to "Evaluate Part Points In Reference State." If this option is selected and the Participation Point is set to AutoCalc = YES, the ParFac for the Participation Point will be evaluated in the contingency reference state and used wherever the ParFac is needed as part of the contingency action.

Bug Fixes

June 26, 2014

Features and Improvements

Contingency Analysis Tool: Deleting a large number of contingencies (10,000s), but now ALL, was very slow. Delete All contingencies was fast and deleting a few was fast, but deleting a large number and not all was very slow. This is fixed.

Sensitivity Calculations: When opening the PTDF dialog, the type is automatically set to Multiple if any directions are defined.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Setting the variable name "EquivLineID" for the object Equiv_Options was not working properly

General: A "stack overflow error" could sometimes result when building a power system equivalent. This has been fixed.

Oneline Diagrams: Fixed an access violation that occurred when drawing an unlinked switched shunt symbol on a oneline

Transient Stability: Continuing to fix the treatment of single phase air conditioner models under extremely low voltages. This impacts CMPLDW, LD1PAC, and CMPLDWNF. Specifically modified so that the "Kcon" curve defined by the parameters Vc1off and Vc2off is used in the algebraic solution of the network boundary equations so that the constant power load does not cause solution failure in the algebraic solution at extremely low voltages.

June 24, 2014

Features and Improvements

Contingency Analysis Tool: Added new contingency action with Injection Groups to drop a specified number of elements in the group.

Contingency Analysis Tool: Added option with Injection Group contingency action to specify when using Merit Order Open if the total MW dropped is allowed to exceed the desired amount or not. Previously, the default was to never exceed the desired amount.

General: Added options with individual Participation Points for Injection Groups to specify the ParFac based on a field of the participant or a Model Expression.

Sensitivity Calculations: When calculating PTDF values added a new MWAtZero:1 field for an interface which is similar to MWAtZero, but it assumes each transfer direction containing an injection group is configured to represent an area and as a result the "net injection" of each injection group in the MWAtZero:1 calculation is assumed to be equal to the export of the most common area in the injection group.

Bug Fixes

Sensitivity Calculations: When opening the PTDF dialog, the type is automatically set to Multiple if any directions are defined.

Sensitivity Calculations: Modified so that the Multiple Direction PTDF value fields for Branch and Interface objects are only available as a field/column if the Direction is marked as "Include = YES". This ensures that when using the script command SaveData with the variable "FGPTDFMult:ALL" or "LinePTDFMult:ALL" that fields are not included for directions that are skipped.

Sensitivity Calculations: Modified Interface field for showing MWAtZero for PTDF calculations to only include Directions marked as "Include = YES" in the calculation.

Transient Stability: Added up to 6 stages for LDST2 model. Previously it only had 3 stages.

Transient Stability: Continuing to fix the treatment of single phase air conditioner models under extremely low voltages. This impacts CMPLDW, LD1PAC, and CMPLDWNF.

June 16, 2014

Features and Improvements

Case Information Displays: With Branch and Transformer tables can now show the regulated bus for a transformer due to ZBR (very low impedance branches) groupings. The ZBR bus is the bus that is actually regulated.

Bug Fixes

Power Flow Solution: Angle smoothing is done when branches are closed to help power flow convergence. Some modifications were made to how this is done to further help convergence.

Transient Stability: For WTGT_A model, fKShaft < 0 is treated as a single mass model.

Transient Stability: Initial speed Wo can now be specified with WTGT_A model. Previously, this was always assumed to be 1.0.

Transient Stability: Fixed initialization of the PRef input to the REEC_A exciter model when (PFlag = 1) is set to model torsional oscillations.

Transient Stability: On the User Defined Model GUI, key fields for user defined model machine models were not getting populated correctly and an access violation could result. This has been fixed.

Transient Stability: If modifying a transient stability load model through an AUX file or SimAuto, a new model would be created with only the fields specified in the file with the remainder of the fields set to defaults instead of only the fields specified for existing objects being updated. This has been fixed.

June 10, 2014

Features and Improvements

Available Transfer Capability (ATC) Tool: Added right-click option on the Transfer Limiters display to "Create Contingent Interface for Selection." This will create interfaces with a monitored branch being the Limiting Element in the Transfer Limiter and the contingent element in the interface being the Contingency Element of the Transer Limiter.

Case Information Displays: Removed the "-CE" from the end of the column header string for custom expressions that have names.

Oneline Diagrams: A line will be drawn through a switched shunt display object if it is on continuous control or an SVC.

Transient Stability: Implemented LDELEC load model.

Bug Fixes

Auxiliary Files (SCRIPT and DATA Sections): Added new parameter "EstimateVoltages" to AppendCase script when appending either an EPC or RAW file. Set this to YES (this is the default) to estimate voltages for newly created buses and to smooth angles across newly created lines or NO not to do this.

File Formats: When appending data from either an EPC or RAW file and using the "with options" file type, an "Estimate voltages at new buses..." option is available to specify if voltages at newly created buses should be estimated and angles should be smoothed across newly created lines. The default is to do this because we assume that you could be appending data from a case with vastly different voltages than the present case. However, in situations where you are appending an entire new island or want to load your own voltage estimates, you do not want Simulator to estimate the voltages that are read in.

Power Flow Solution: A single bus system with both a generator and load should solve without giving the blackout message. Previously, a log message would indicate that the power flow solved but the blackout message would still appear.

Transient Stability: Added support for properly reading and writing the measured bus and measured branch specification in a DYD file for the REPC_A model.

Transient Stability: Fixed a bug with enforcing non-windup limits in the REPC_A model.

June 4, 2014

Features and Improvements

Case Information Displays: Modified so that the Selected field can be edited or toggled while iin Difference or Base Case mode for the Difference Flows tool.

Contingency Analysis Tool: Added an option to auto-insert contingencies and name them by label.

Fault Analysis: Added an option to auto-insert faults and name them by label.

Oneline Diagrams: While in Run Mode, left clicking on a bus name or number field will open the Bus View for that bus.

Sensitivity Calculations: Added LODF Screening tool to screen single line contingencies by LODF magnitude or loading. Pairs of contingencies can be created from contingencies that are deemed to be significant based on screening thresholds. Purpose is to create a more manageable list of contingencies rather than run all pairs of single contingencies.

Transient Stability: Added an option to auto-insert transient contingencies and name them by label.

User Interface Dialogs: In Set Selected from Network Cut tool, added option to prompt user asking if they would like to initialize the Selected field.

User Interface Dialogs: Added Line length information on Branch Information dialog while in Run mode.

Bug Fixes

Contingency Analysis: When using one of the linear solution techniques or when solving in dc power flow mode, the impact of contingencies that closed lines was not being correctly calculated. This has been fixed.

User Interface Dialogs: When using the equivalencing tool to save out a portion of the system to a PWB file, an error could result when appending the file to another case if transient stability data existed in the original system. Transient stability data is now currently not stored with the portion of the system saved to file.